NHPC BMLT cheat sheet

Fasting plasma glucose diagnostic thresholds: normal <100 mg/dL, impaired fasting glucose 100–125 mg/dL, diabetes ≥126 mg/dL on two occasions; random ≥200 mg/dL with symptoms is diagnostic.

HbA1c reflects mean glycemia over the preceding ~120 days (RBC lifespan); NGSP/DCCT-aligned results should be standardized, and values ≥6.5% support diabetes diagnosis.

Enzymatic reference patterns: ALT > AST suggests hepatocellular injury; AST:ALT >2 with raised GGT and ALP suggests alcohol-related liver disease; ALP rise with normal GGT points to bone origin.

Cardiac troponin I/T is the preferred necrosis marker (high specificity); CK-MB rises earlier historically but is less cardiac-specific; myoglobin is sensitive but nonspecific.

Renal panel: urea and creatinine both rise in prerenal azotemia but urea:creatinine ratio >20:1 favors prerenal; eGFR (CKD-EPI) stages CKD, with <60 mL/min/1.73 m² for ≥3 months defining CKD.

Electrolyte rules: anion gap = Na − (Cl + HCO3), normal 8–12 mmol/L; raised gap with metabolic acidosis suggests ketoacidosis, lactate, uremia, or toxins; normal-gap acidosis suggests bicarbonate loss.

Lipid targets: LDL calculated by Friedewald (valid when triglycerides <400 mg/dL); direct LDL or non-HDL cholesterol is used when triglycerides are high.

Thyroid testing: TSH is the first-line screen; primary hypothyroidism shows high TSH with low free T4, while subclinical hypothyroidism shows high TSH with normal free T4.

Specimen handling: potassium rises with hemolysis or delayed separation; glucose falls with delayed separation due to glycolysis, so fluoride-oxalate tubes or rapid processing are used.

Gram stain interpretation: purple = gram-positive (thick peptidoglycan), pink/red = gram-negative (thin peptidoglycan, outer membrane); shape and arrangement (cocci in clusters vs chains, bacilli) guide presumptive identification.

Catalase and coagulase: Staphylococcus is catalase-positive; S. aureus is coagulase-positive, whereas coagulase-negative staphylococci (e.g., S. epidermidis) are less pathogenic but important in device infections.

Streptococcal classification: bacitracin sensitivity and PYR positivity suggest group A (S. pyogenes); optochin sensitivity and bile solubility identify S. pneumoniae; bile-esculin positivity suggests group D enterococci.

Culture media: MacConkey agar selects gram-negatives and differentiates lactose fermenters (pink) from non-fermenters (colorless); blood agar shows hemolysis (beta complete, alpha partial, gamma none).

Mycobacteriology: acid-fast bacilli stain with Ziehl-Neelsen or auramine; culture on Löwenstein-Jensen or liquid MGIT is slow, so molecular assays (e.g., NAAT) speed detection.

Virology diagnostics: molecular NAAT/PCR detects viral nucleic acid with high sensitivity; serology (IgM/IgG) indicates acute versus past infection; viral culture and antigen tests are alternatives.

Mycology basics: KOH mounts show fungal hyphae; Sabouraud dextrose agar is standard; germ-tube positivity at 37°C supports Candida albicans; Aspergillus shows septate hyphae with acute-angle branching.

Parasitology: stool microscopy with iodine and saline wet mounts detects cysts and trophozoites; modified acid-fast staining identifies Cryptosporidium; thick and thin blood films detect malaria parasites.

Complete blood count reference approach: hemoglobin, hematocrit, and RBC indices (MCV, MCH, MCHC) classify anemia as microcytic (MCV <80 fL), normocytic (80–100 fL), or macrocytic (>100 fL).

Iron studies: iron deficiency shows low ferritin, low serum iron, high TIBC, and low transferrin saturation; anemia of chronic disease shows normal/high ferritin with low TIBC.

Reticulocyte count distinguishes hypoproliferative from hemolytic/blood-loss anemia; corrected reticulocyte count and reticulocyte production index adjust for anemia severity.

Coagulation: PT/INR monitors warfarin (extrinsic pathway, factors II, V, VII, X), and aPTT monitors unfractionated heparin (intrinsic pathway); mixing studies help detect inhibitors.

ABO compatibility: group O is universal donor for red cells, group AB is universal recipient; plasma compatibility is reversed (AB plasma is universal donor).

Crossmatch and antibody screen: the indirect antiglobulin test detects unexpected antibodies; a positive screen requires identification and antigen-negative units.

Transfusion reactions: acute hemolytic reaction presents with fever, chills, flank pain, and hemoglobinuria; stop the transfusion, maintain venous access, and report immediately.

Platelet and plasma storage: platelets are stored at 20–24°C with agitation for about 5 days; fresh frozen plasma is stored frozen and thawed before use.

Urinalysis sequence: physical (color, clarity, specific gravity), chemical dipstick (pH, protein, glucose, ketones, blood, leukocyte esterase, nitrite), then microscopic sediment examination.

Urine specific gravity by reagent strip correlates with ionic concentration; refractometry is more accurate; isosthenuria (~1.010) indicates impaired concentrating ability.

CSF analysis: normal is clear, glucose ~60% of blood glucose, protein 15–45 mg/dL, and cell count low; bacterial meningitis shows neutrophilic pleocytosis, low glucose, and high protein.

Transudate versus exudate by Light's criteria: pleural fluid protein/serum protein >0.5, fluid LDH/serum LDH >0.6, or fluid LDH >2/3 upper normal serum LDH indicates exudate.

Semen analysis parameters include volume, concentration, motility, and morphology; results are interpreted against WHO reference limits and require proper abstinence and collection.

Stool examination: occult blood testing detects gastrointestinal bleeding; microscopic examination for ova and parasites requires fresh specimens and appropriate preservatives.

Synovial fluid: normal is clear and viscous; septic arthritis shows turbid fluid with high WBC count and neutrophil predominance; crystals (monosodium urate, calcium pyrophosphate) are examined under polarized light.

Body fluid cell counts should be performed promptly because cells lyse; use a hemocytometer or automated analyzer with appropriate diluent for each fluid type.

Tissue processing sequence: fixation (10% neutral buffered formalin), dehydration in graded alcohols, clearing in xylene, paraffin infiltration, embedding, sectioning (3–5 µm), staining, and coverslipping.

H&E staining: hematoxylin is a basic dye staining nuclei blue-purple; eosin is acidic and stains cytoplasm and collagen pink.

Fixation prevents autolysis and preserves morphology; the fixative volume should be about 10 times the tissue volume, and fixation time affects antigen retrieval for immunohistochemistry.

Frozen sections provide rapid intraoperative diagnosis; they are less crisp than paraffin sections and are used for margin assessment and tissue triage.

Cytology: Pap smears screen for cervical dysplasia; the Bethesda system reports categories from NILM through ASC-US, LSIL, HSIL, and carcinoma.

Fine-needle aspiration cytology is minimally invasive and useful for thyroid, breast, and lymph node lesions; inadequate samples require repeat or core biopsy.

Special stains: PAS highlights glycogen and fungi, Ziehl-Neelsen detects acid-fast bacilli, and Congo red demonstrates amyloid with apple-green birefringence under polarized light.

Immunohistochemistry uses antigen-antibody reactions with chromogenic detection; appropriate controls and antigen retrieval are essential for valid interpretation.

Spectrophotometry follows Beer-Lambert law: absorbance is proportional to concentration and path length; the assay must be read at the analyte's absorption maximum.

Quality control of spectrophotometers includes wavelength accuracy (holmium or didymium filters) and linearity/stray-light checks.

Automated chemistry analyzers use spectrophotometric, ion-selective electrode, or turbidimetric principles; calibration curves must be validated before patient testing.

Centrifuges require balancing of tubes, correct rotor speed (RPM converted to relative centrifugal force), and regular tachometer and timer verification.

Analytical balances, pipettes, and water baths are verified with certified weights, gravimetric checks, and calibrated thermometers respectively.

pH meters are calibrated with fresh standard buffers at two or three points; electrode storage and temperature compensation affect readings.

Hematology analyzers use electrical impedance or flow cytometry; flags indicate abnormal populations and require manual smear review.

Microscopes require Köhler illumination alignment, correct condenser and objective matching, and periodic cleaning; resolution depends on numerical aperture and wavelength.

Internal quality control uses control materials at normal and abnormal levels; Westgard rules (1-2s, 1-3s, 2-2s, R-4s, 4-1s, 10x) define rejection criteria.

Levey-Jennings charts plot control values over time; shifts indicate sudden systematic error, while trends indicate gradual drift or reagent deterioration.

External quality assessment (proficiency testing) compares results with peer laboratories; unacceptable performance requires root-cause analysis and corrective action.

Total analytical error combines bias and imprecision; the allowable total error is set by clinical or regulatory criteria (e.g., CLIA).

Method validation includes accuracy, precision, linearity, analytical sensitivity, specificity, and interference studies before clinical use.

The quality management system follows ISO 15189 principles: document control, competency records, equipment maintenance, and continuous improvement.

Laboratory safety: standard precautions apply to all specimens; chemical hygiene plans and biological spill procedures are documented and practiced.

Turnaround time, specimen rejection rates, and critical value reporting are key performance indicators monitored by laboratory management.

Antibody structure: IgG is the most abundant and crosses the placenta; IgM is the first antibody in primary infection and is pentameric; IgA is secretory; IgE mediates allergy; IgD is a B-cell receptor.

Primary immune response is slow with IgM predominance; secondary response is rapid with high-affinity IgG, which is why booster doses and prior exposure matter.

Agglutination tests (e.g., blood typing) detect antibodies against particulate antigens; precipitation and turbidimetry detect soluble antigen-antibody complexes.

ELISA formats: direct, indirect, sandwich, and competitive; enzyme-labeled detection produces a color change proportional to analyte, read on a microplate reader.

Complement fixation, immunofluorescence, and chemiluminescence are alternative serologic methods; each has different sensitivity and interference profiles.

Autoimmune testing: antinuclear antibody (ANA) is a screening test; anti-dsDNA and anti-Sm are specific for systemic lupus erythematosus.

Hypersensitivity types: I (IgE, immediate), II (antibody-mediated, cytotoxic), III (immune complex), IV (T-cell mediated, delayed).

Serology limitations include cross-reactivity, prozone and postzone phenomena, and the window period before antibody becomes detectable.

Informed consent requires capacity, disclosure of material information, comprehension, and voluntariness; consent may be implied in emergencies.

Confidentiality is a core duty; disclosure is permitted with patient consent, for legally mandated reporting, or when required by law.

Professional boundaries: conflicts of interest, gifts, and dual relationships must be avoided or disclosed; patient welfare takes priority.

Medical negligence requires a duty of care, breach of standard, causation, and damages; documentation is central to defense and quality improvement.

Mandatory reporting obligations include certain communicable diseases, child abuse, and occupational injuries, as defined by local public health law.

Patient rights include access to records, privacy, respectful care, and the ability to refuse treatment; minors and incapacitated adults require special provisions.

Research ethics: institutional review board approval, informed consent, and protection of vulnerable populations are required before human-subject research.

Laboratory professionals are accountable for accurate reporting, error disclosure, and maintaining competence through continuing education.

Cell injury: reversible changes include swelling and fatty change; irreversible injury involves membrane damage, mitochondrial failure, and apoptosis or necrosis.

Inflammation: acute inflammation features vasodilation, increased permeability, and neutrophil infiltration; chronic inflammation features lymphocytes, macrophages, and fibrosis.

Neoplasia: benign tumors are well circumscribed and non-invasive; malignant tumors show invasion, metastasis, and anaplasia; grading describes differentiation and staging describes spread.

Cardiovascular physiology: cardiac output = heart rate × stroke volume; blood pressure = cardiac output × systemic vascular resistance.

Renal physiology: glomerular filtration rate depends on net filtration pressure; the proximal tubule reabsorbs most filtered sodium, water, and glucose.

Pharmacokinetics: absorption, distribution, metabolism (often hepatic CYP enzymes), and excretion determine drug levels; half-life governs dosing intervals.

Pharmacodynamics: agonists activate receptors, antagonists block them; therapeutic index reflects the margin between effective and toxic doses.

Respiratory physiology: oxygen transport depends on hemoglobin, PaO2, and the oxyhemoglobin dissociation curve; carbon dioxide transport is mainly as bicarbonate.

Incidence measures new cases over a period; prevalence measures all existing cases at a point in time; prevalence ≈ incidence × duration for stable conditions.

Relative risk is used in cohort studies; odds ratio is used in case-control studies; both estimate association but are interpreted differently.

Sensitivity = TP/(TP+FN); specificity = TN/(TN+FP); positive predictive value depends on prevalence, so screening programs must account for it.

Outbreak investigation steps: verify diagnosis, define cases, describe time-place-person, generate hypotheses, and implement control measures.

Herd immunity threshold depends on basic reproduction number (R0) and vaccine efficacy; higher R0 requires higher coverage.

Standard precautions apply to all patients; transmission-based precautions (contact, droplet, airborne) are added according to the pathogen.

Hand hygiene is the single most effective infection control measure; alcohol-based rubs are preferred when hands are not visibly soiled.

Surveillance and notification systems detect emerging infections; healthcare-associated infection rates are monitored through standardized definitions.

Urine dipstick nitrite positivity suggests nitrate-reducing gram-negative bacteriuria; leukocyte esterase indicates pyuria; both together increase the likelihood of urinary tract infection.

Urine protein dipstick is most sensitive to albumin; Bence Jones proteins may be missed, so sulfosalicylic acid or urine protein electrophoresis is used when myeloma is suspected.

Cerebrospinal fluid should be collected in numbered tubes; cell counts and differential are performed promptly, and a traumatic tap shows decreasing RBC counts across tubes.

Pleural fluid pH <7.2 with low glucose and high LDH suggests complicated parapneumonic effusion or empyema requiring drainage.

Ascitic fluid: serum-ascites albumin gradient ≥1.1 g/dL indicates portal hypertension; lower values suggest peritoneal disease such as malignancy or tuberculosis.

Semen analysis follows WHO reference limits; abstinence time of 2–7 days is standard, and results should be confirmed on a repeat sample.

Stool occult blood immunochemical tests are more specific than guaiac tests because they detect human hemoglobin and avoid dietary interference.

Synovial fluid crystal examination: monosodium urate crystals are needle-shaped and negatively birefringent; calcium pyrophosphate crystals are rhomboid and positively birefringent.

Fixation time and formalin concentration affect staining and immunohistochemistry; overfixation can mask antigens and require stronger retrieval.

Decalcification of bone uses acid or chelating agents; prolonged acid exposure damages nuclear staining and antigenicity.

Frozen section artifacts include ice crystals, chatter, and folds; they must be recognized so they are not misinterpreted as pathology.

Cytology specimen adequacy depends on cellularity and preservation; liquid-based cytology reduces obscuring blood and allows ancillary testing.

Grading versus staging: grade describes tumor differentiation; stage describes anatomic extent and is the stronger prognostic factor.

Frozen section is used for intraoperative margin assessment and lymph node evaluation; discordance with paraffin sections should be reviewed.

Special stains: reticulin highlights reticulin fibers, Masson trichrome highlights collagen, and Prussian blue detects hemosiderin.

Cytology reporting uses standardized categories; Bethesda cervical cytology and thyroid Bethesda systems guide management and follow-up.

Beer-Lambert law: A = εbc; absorbance is linear only within the validated range, so diluted samples must be repeated when results exceed linearity.

Ion-selective electrodes measure electrolytes by potentiometry; indirect ISE dilutes the sample and can be affected by hyperlipidemia or hyperproteinemia.

Turbidimetry and nephelometry measure light scatter or attenuation by particles; nephelometry is more sensitive for low-concentration analytes.

Flow cytometry uses hydrodynamic focusing and fluorochrome-labeled antibodies; compensation and isotype controls are needed for valid interpretation.

Centrifuge relative centrifugal force = 1.118 × 10⁻⁵ × r (cm) × RPM²; balancing and rotor derating are required for safety.

Calibration versus calibration verification: calibration establishes the curve, while verification confirms the curve remains valid after maintenance or reagent change.

Temperature monitoring of refrigerators, incubators, and water baths requires calibrated devices and documented records.

Electrical safety includes grounding, leakage-current testing, and inspection of cords and plugs; biomedical equipment must be serviced per schedule.

Westgard 1-3s rule rejects a run when one control exceeds ±3 SD; 2-2s rejects when two consecutive controls exceed ±2 SD on the same side.

R-4s rule detects random error when the range between two controls exceeds 4 SD; 4-1s and 10x detect systematic error.

Control material must be commutable and stored per manufacturer instructions; expired or improperly stored controls invalidate the run.

External quality assessment performance should be reviewed for bias; persistent bias requires recalibration or method review.

Document control ensures only current procedures are in use; obsolete documents are archived and staff are trained on revisions.

Competency assessment includes direct observation, result review, and blind sample testing; new staff require verification before independent reporting.

Critical value reporting requires documented notification to the responsible clinician within a defined time frame.

Risk management uses failure mode analysis and incident reporting to prevent recurrence of laboratory errors.

Antigen-antibody binding is specific and reversible; affinity describes strength of a single binding site, and avidity describes overall binding strength.

Monoclonal antibodies are produced by hybridoma technology; polyclonal antibodies recognize multiple epitopes and are more prone to cross-reactivity.

Complement activation: classical pathway is triggered by IgG/IgM immune complexes, alternative by microbial surfaces, and lectin by mannose patterns.

Prozone phenomenon occurs with excess antibody and can cause false-negative agglutination; dilution resolves it.

Immunoassays can be affected by heterophile antibodies, rheumatoid factor, and biotin interference; blocking reagents and alternative methods reduce risk.

HIV testing algorithm uses a sensitive screening immunoassay followed by a confirmatory differentiation assay; indeterminate results require follow-up.

Hepatitis B serology: HBsAg indicates infection, anti-HBs indicates immunity, and anti-HBc IgM indicates acute infection.

Allergy testing: specific IgE immunoassays and skin prick tests detect sensitization; results must be interpreted with clinical history.

Informed refusal is as valid as informed consent when the patient has capacity and understands the consequences.

Breach of confidentiality may be justified when there is a duty to warn or protect an identifiable third party at risk.

Negligence standard is the care expected of a reasonably competent practitioner in the same field, not perfection.

Documentation should be contemporaneous, objective, and complete; alterations must be dated and attributed, never erased.

Consent for minors: parental or guardian consent is generally required, with exceptions for emancipated minors and certain public health situations.

Professional misconduct includes falsifying results, practicing beyond competence, and failing to disclose errors that affect patient care.

Health law governs licensure, scope of practice, and mandatory reporting; laboratory personnel must know their jurisdiction's requirements.

Research and quality-improvement projects require ethical review when they involve identifiable patient data or deviation from standard care.

Cell cycle: DNA replication occurs in S phase; mitotic spindle checkpoint ensures chromosome segregation; loss of checkpoint control promotes aneuploidy.

Apoptosis is energy-dependent and caspase-mediated with cell shrinkage and membrane blebbing; necrosis is passive with swelling and inflammation.

Hemostasis: platelet adhesion, activation, and aggregation form the primary plug; the coagulation cascade reinforces it with fibrin.

Acid-base: respiratory acidosis shows low pH and high PaCO2; metabolic acidosis shows low pH and low HCO3; compensation follows the opposite system.

Nephrotoxic drugs include aminoglycosides, amphotericin B, and NSAIDs; hepatotoxic drugs include paracetamol overdose, isoniazid, and methotrexate.

Antibiotic mechanisms: beta-lactams inhibit cell wall synthesis, aminoglycosides inhibit protein synthesis, fluoroquinolones inhibit DNA gyrase, and rifampicin inhibits RNA polymerase.

Tumor suppressor genes (e.g., TP53, RB1) normally restrain cell growth; loss of function contributes to malignancy.

Body fluid compartments: intracellular fluid is about two-thirds of total body water; sodium is the main extracellular cation and potassium the main intracellular cation.

Epidemiologic study designs: cross-sectional measures prevalence, cohort measures incidence and relative risk, case-control measures odds ratio, and randomized trials test interventions.

Bias types include selection bias, information bias, and confounding; randomization and matching reduce confounding.

Screening test criteria include high sensitivity, acceptable specificity, treatable disease, and a suitable preclinical phase.

Outbreak control measures include isolation, cohorting, contact tracing, and environmental cleaning according to transmission route.

Airborne precautions require N95 respirators and negative-pressure rooms; droplet precautions require surgical masks and spatial separation.

Sterilization versus disinfection: sterilization destroys all microorganisms including spores; high-level disinfection destroys most but not all spores.

Vaccination programs require cold-chain maintenance and monitoring; vaccine effectiveness is assessed through surveillance and coverage data.

Healthcare-associated infections are prevented by hand hygiene, aseptic technique, device care bundles, and antimicrobial stewardship.

Liver function: bilirubin fractionation distinguishes prehepatic (unconjugated) from hepatic and posthepatic (conjugated) hyperbilirubinemia; urine bilirubin is absent in hemolysis.

Pancreatic markers: amylase and lipase rise in acute pancreatitis; lipase is more specific and remains elevated longer.

Tumor markers: AFP for hepatocellular carcinoma, CA-125 for ovarian cancer, CEA for colorectal cancer, and PSA for prostate cancer; none is a stand-alone diagnostic test.

Blood gas interpretation: stepwise assessment of pH, PaCO2, HCO3, and compensation; anion gap and delta gap refine the metabolic diagnosis.

Diabetes monitoring: fasting glucose, 2-hour OGTT, HbA1c, and random glucose with symptoms are accepted diagnostic approaches; repeat testing is required when asymptomatic.

Enzyme units and reference intervals are method-dependent; results should be interpreted using the laboratory's own validated reference ranges.

Specimen collection: tourniquet time should be short; prolonged stasis raises potassium, protein, and lipid values.

Interference: hemolysis raises potassium, LDH, and AST; lipemia interferes with many spectrophotometric assays; icterus affects some creatinine methods.

Antimicrobial susceptibility testing: disk diffusion (Kirby-Bauer) requires standardized inoculum and zone interpretation; MIC methods include broth dilution and E-test.

MRSA is detected by cefoxitin disk or oxacillin MIC; ESBL and carbapenemase detection uses phenotypic and molecular methods.

Blood culture collection: two to three sets from separate sites before antibiotics; volume of blood is the most important factor for yield.

Urine culture colony counts: ≥10⁵ CFU/mL suggests infection in clean-catch specimens; lower counts may be significant in symptomatic patients.

Viral hepatitis serology: HAV IgM indicates acute infection; HCV RNA confirms current infection; HDV requires HBsAg.

Fungal culture and microscopy: dermatophytes grow on Sabouraud agar; Cryptococcus is identified by India ink and latex antigen testing.

Malaria diagnosis: thick films detect parasites, thin films identify species; rapid antigen tests detect Plasmodium antigens but cannot quantify parasitemia.

Stool culture for enteric pathogens uses selective media such as MacConkey, XLD, and TCBS; enrichment improves recovery of Salmonella.

Peripheral smear review: target cells suggest thalassemia or liver disease; schistocytes suggest microangiopathic hemolysis; sickle cells suggest hemoglobinopathy.

Leukocyte differential: neutrophilia suggests bacterial infection or stress; lymphocytosis suggests viral infection; eosinophilia suggests allergy or parasites.

Platelet disorders: thrombocytopenia may be due to decreased production, increased destruction, or sequestration; pseudo-thrombocytopenia from EDTA clumping should be excluded.

Bone marrow interpretation requires correlation with peripheral counts and clinical history; iron stores are assessed with Prussian blue staining.

Blood component storage: red cells at 1–6°C for up to 35–42 days depending on preservative; whole blood-derived platelets at 20–24°C with agitation.

Pretransfusion testing includes ABO/Rh typing, antibody screen, and crossmatch; electronic crossmatch is permitted when criteria are met.

Delayed hemolytic transfusion reaction occurs days after transfusion due to anamnestic antibody response; it presents with falling hemoglobin and rising bilirubin.

Massive transfusion protocols balance red cells, plasma, and platelets and monitor for hypocalcemia, hypothermia, and dilutional coagulopathy.

Urine microscopy: RBC casts indicate glomerulonephritis; WBC casts indicate pyelonephritis; hyaline casts are nonspecific and may occur in normal urine.

Urine pH and crystals: acidic urine favors uric acid and cystine crystals; alkaline urine favors calcium phosphate and struvite crystals.

CSF lactate rises in bacterial meningitis and can help distinguish it from viral meningitis when cultures are pending.

Pleural fluid adenosine deaminase is elevated in tuberculous pleuritis; cytology and culture are required for confirmation.

Peritoneal dialysis effluent and ascitic fluid should be examined for cell count and differential; neutrophil predominance suggests infection.

Semen analysis: viscosity, liquefaction time, volume, pH, concentration, motility, and morphology are reported; abnormal results require repeat testing.

Stool testing for Clostridioides difficile uses toxin immunoassay or NAAT; testing asymptomatic patients is not recommended.

Body fluid glucose should be compared with a simultaneously drawn serum glucose; low ratios suggest infection or malignancy.

Tissue orientation and inking of margins are performed by the pathologist before processing; accurate orientation is essential for margin reporting.

Section thickness of 3–5 µm allows light microscopy; thicker sections reduce resolution and increase overlap.

Cryostat temperature is typically −20 to −25°C; inappropriate temperature causes freezing artifacts or poor sectioning.

Cytology fixatives: alcohol-based fixatives preserve nuclear detail; air-dried smears are used for Romanowsky stains.

Ancillary testing on cytology specimens includes HPV testing, immunocytochemistry, and molecular assays; cell block preparation increases yield.

Histological grading of tumors uses mitotic count, nuclear pleomorphism, and differentiation; staging uses TNM or equivalent systems.

Artifacts such as formalin pigment and section folds must be distinguished from true pathology; polarized light helps identify formalin pigment.

Quality assurance in histopathology includes slide review, turnaround time monitoring, and correlation with cytology and frozen section results.

Spectrophotometer components: light source, monochromator, cuvette, detector, and readout; cuvette quality and cleanliness affect absorbance.

Ion-selective electrode maintenance includes membrane replacement and calibration with standard solutions; drift indicates electrode failure.

Automated analyzers require daily maintenance, reagent inventory control, and probe cleaning; carryover between samples can cause false results.

Pipette calibration is performed gravimetrically with distilled water at a controlled temperature; accuracy and precision are both assessed.

Thermometers and timers used in the laboratory must be calibrated against reference standards and records retained.

Electrical safety testing includes protective earth resistance and leakage current; equipment with damaged cords must be removed from service.

Microscope maintenance includes cleaning lenses with appropriate solvent, checking alignment, and replacing bulbs per manufacturer specifications.

Laboratory information systems require validation, access control, and audit trails to protect data integrity.

Statistical QC: mean and SD are established from at least 20 data points under stable conditions; control limits are set at ±2 SD and ±3 SD.

Westgard multirule application should be tailored to the analyte's clinical importance; high-risk analytes may require stricter rules.

Proficiency testing samples must be handled like patient samples; results must not be shared between laboratories.

Corrective action documentation includes root cause, action taken, and effectiveness check; repeat failures require method review.

Quality indicators include specimen rejection rate, turnaround time, amended reports, and customer complaints.

Personnel records include qualifications, training, competency, and continuing education; competency is reassessed at defined intervals.

Equipment maintenance schedules and calibration records are part of the quality management system and are reviewed during audits.

Biosafety levels and waste segregation follow institutional policy and national regulations; sharps are disposed of in puncture-resistant containers.

Immunoglobulin classes: IgG crosses the placenta and provides neonatal immunity; IgM is too large to cross the placenta and indicates recent infection.

Complement deficiency increases susceptibility to encapsulated organisms; C3 and C4 levels are measured in suspected deficiency.

Autoimmune serology: rheumatoid factor and anti-CCP support rheumatoid arthritis; anti-CCP is more specific.

Celiac disease serology: tissue transglutaminase IgA with total IgA to exclude IgA deficiency; duodenal biopsy confirms diagnosis.

Syphilis serology: nontreponemal tests (RPR, VDRL) are used for screening and monitoring; treponemal tests confirm infection.

Dengue serology: IgM indicates recent infection; NS1 antigen is detectable early in infection; cross-reactivity with other flaviviruses is possible.

Immunodeficiency evaluation includes quantitative immunoglobulins, lymphocyte subsets, and functional assays; results guide treatment.

Point-of-care serology tests require quality control and confirmation of positive results with laboratory-based methods.

Duty of care arises when a professional relationship is established; abandonment occurs when care is withdrawn without adequate notice or referral.

Informed consent for procedures should document risks, benefits, alternatives, and the patient's questions and decision.

Privacy laws protect identifiable health information; minimum necessary disclosure and secure storage are required.

Whistleblowing may be ethically justified when patient safety is at risk and internal channels have failed.

Professional codes require honesty in reporting, avoidance of plagiarism, and acknowledgment of errors.

Conflict-of-interest disclosure is required for research, publications, and procurement decisions.

Consent and confidentiality apply to teaching and case presentations; identifiers should be removed where possible.

Legal reporting requirements vary by jurisdiction; laboratory staff should consult institutional policy and public health authorities.

Cardiac cycle: systole includes isovolumetric contraction and ejection; diastole includes isovolumetric relaxation and filling; heart sounds reflect valve closure.

Renal regulation: aldosterone increases sodium reabsorption and potassium excretion; ADH increases water reabsorption; ANP promotes sodium excretion.

Respiratory control: medullary respiratory centers respond to CO2 and pH; peripheral chemoreceptors respond primarily to hypoxia.

Pharmacology: first-pass metabolism reduces oral bioavailability; prodrugs require metabolic activation; inducers and inhibitors alter drug levels.

Pathology of atherosclerosis: endothelial injury, lipid accumulation, inflammation, and plaque formation; rupture causes thrombosis.

Cell adaptation: hypertrophy increases cell size, hyperplasia increases cell number, metaplasia changes cell type, and dysplasia indicates disordered growth.

Antimicrobial resistance mechanisms include enzyme inactivation, efflux pumps, target modification, and reduced permeability.

Fluid and electrolyte balance: hyponatremia may be hypovolemic, euvolemic, or hypervolemic; treatment depends on volume status and chronicity.

Attack rate = new cases among exposed or at-risk population during an outbreak; it is useful for foodborne and point-source outbreaks.

Case fatality rate = deaths from a disease divided by diagnosed cases; it differs from mortality rate, which uses the total population.

Screening versus diagnostic testing: screening tests are applied to asymptomatic populations, while diagnostic tests confirm disease in symptomatic patients.

Contact tracing identifies exposed individuals and interrupts transmission; the incubation period determines the tracing window.

Vaccine types include live attenuated, inactivated, toxoid, subunit, and mRNA; live vaccines are generally avoided in immunocompromised patients.

Environmental infection control includes cleaning, disinfection, and sterilization according to Spaulding classification of devices.

Antimicrobial stewardship reduces resistance by promoting appropriate selection, dose, and duration of therapy.

Public health surveillance systems collect, analyze, and disseminate data for action; notifiable diseases are reported to health authorities.

Urine collection: first-morning midstream specimen is preferred for routine analysis; 24-hour collection requires proper preservative and complete volume recording.

Urine dipstick blood positivity may reflect hematuria, hemoglobinuria, or myoglobinuria; microscopy distinguishes red cells from pigment.

CSF opening pressure, appearance, cell count, glucose, protein, and culture are core tests; xanthochromia suggests prior hemorrhage.

Pleural fluid pH should be measured with a blood gas analyzer; improper handling alters pH and glucose results.

Ascitic fluid cell count with differential: polymorphonuclear count ≥250 cells/mm³ suggests spontaneous bacterial peritonitis.

Semen analysis should be performed within 1 hour of collection when possible; temperature and liquefaction affect motility assessment.

Stool osmotic gap helps distinguish osmotic from secretory diarrhea; osmotic diarrhea improves with fasting.

Synovial fluid Gram stain and culture are essential in suspected septic arthritis; negative culture does not exclude infection.

Reference intervals are established from a healthy population and should be method- and age-specific; pediatric and pregnancy ranges differ from adult ranges.

Critical values in biochemistry include severe hypo- or hyperkalemia, severe hypoglycemia, and marked acidosis; they require immediate notification.

Enzyme kinetics: reaction rate is measured under zero-order conditions with excess substrate; substrate depletion causes nonlinear results.

Interference from drugs and metabolites can cause false results; delta checks and clinical correlation help detect errors.

HbA1c methods must be NGSP-certified; hemoglobin variants and conditions affecting RBC survival alter results.

Lipid testing should follow a 9–12 hour fast when triglycerides are measured; non-HDL cholesterol does not require fasting.

Tumor marker results should not be used for screening asymptomatic populations; they are used for monitoring and follow-up.

Traceability of calibrators to reference materials supports comparability of results across laboratories.

Specimen quality: sputum is acceptable for culture when many neutrophils and few epithelial cells are seen on Gram stain.

Anaerobic culture requires prompt transport in anaerobic containers; specimens from normally sterile sites are preferred.

Mycoplasma and Chlamydia are not detected by routine bacterial culture; molecular methods are preferred.

Viral load assays quantify nucleic acid and are used to monitor HIV, HBV, and HCV treatment response.

Fungal identification combines colony morphology, microscopy, and biochemical or molecular tests; dimorphic fungi grow as molds at 25°C and yeasts at 37°C.

Parasite diagnosis: Giardia antigen testing is more sensitive than microscopy; Cryptosporidium requires modified acid-fast staining.

Infection control in the microbiology laboratory includes biosafety cabinets for aerosol-generating procedures and proper waste disposal.

Antimicrobial susceptibility reporting should follow current breakpoints; outdated breakpoints can mislead therapy.

Anemia classification by reticulocyte count: low reticulocyte count suggests production defect; high count suggests destruction or blood loss.

Microcytic anemia differential: iron deficiency, thalassemia, and anemia of chronic disease; ferritin and hemoglobin electrophoresis help distinguish.

Macrocytic anemia differential: vitamin B12 or folate deficiency, liver disease, alcohol, and drugs; peripheral smear shows oval macrocytes and hypersegmented neutrophils in megaloblastic anemia.

Hemolytic anemia markers include raised reticulocytes, indirect bilirubin, and LDH, with low haptoglobin.

Coagulation testing: mixing study corrects in factor deficiency and fails to correct in the presence of an inhibitor.

Blood group systems beyond ABO include Rh, Kell, Duffy, and Kidd; clinically significant antibodies can cause hemolytic reactions.

Transfusion reaction workup includes clerical check, repeat ABO typing, direct antiglobulin test, and culture if bacterial contamination is suspected.

Patient identification at the bedside is the most important safeguard against wrong-blood transfusion.

Urine reagent strips should be read at the manufacturer's specified time; delayed reading causes false-positive results.

Urine protein-to-creatinine ratio estimates 24-hour protein excretion and avoids collection errors.

CSF bacterial antigen testing is less sensitive than culture and NAAT; it is not a substitute for culture.

Pleural fluid is sent for cell count, protein, LDH, glucose, pH, cytology, and culture; each test requires appropriate tube and handling.

Ascitic fluid should be inoculated into blood culture bottles at the bedside to improve culture yield.

Semen analysis reference limits are based on the lower fifth percentile of fertile men; values below the limit do not prove infertility.

Stool culture and parasite examination require appropriate transport media; delayed processing reduces recovery.

Synovial fluid cell count and differential help distinguish inflammatory from noninflammatory joint disease.

Formalin fixation cross-links proteins and preserves tissue architecture; antigen retrieval reverses some cross-linking for immunohistochemistry.

Paraffin embedding requires complete dehydration and clearing; residual water causes poor sectioning.

Microtome blade angle and clearance angle affect section quality; dull blades cause tears and chatter.

H&E staining differentiation: excess hematoxylin causes overstaining; acid alcohol removes excess dye.

Cytology specimens include exfoliative (Pap, sputum, urine) and aspiration (FNA) samples; each has specific processing requirements.

Immunocytochemistry on cytology requires validated protocols; cell blocks provide better controls than smears.

Tumor staging systems include TNM; staging is more predictive of prognosis than grading.

Quality control in cytology includes screening limits, rescreening of negative cases, and correlation with histology.

Spectrophotometer linearity should be verified with calibrated filters or standard solutions; nonlinearity causes inaccurate high results.

Stray light limits the upper absorbance range; instruments should be checked with a stray-light standard.

Ion-selective electrodes require daily calibration and periodic membrane replacement; protein buildup causes drift.

Automated analyzers use sample and reagent probes with liquid-level sensing; clogged probes cause sampling errors.

Pipette accuracy and precision should be checked at the intended volume; different tips can affect performance.

Centrifuge speed should be verified with a tachometer; incorrect speed affects cell separation and platelet-poor plasma preparation.

pH meter calibration should use fresh buffers and temperature compensation; electrode fouling causes slow response.

Microscope numerical aperture and condenser alignment determine resolution; oil immersion requires oil with matching refractive index.

QC frequency should be based on the stability of the method and clinical risk; some analytes require daily or per-shift QC.

Patient-based QC using delta checks and moving averages can detect errors between control runs.

Calibration frequency depends on method stability; recalibration is required after major maintenance or reagent lot change.

Lot-to-lot verification of reagents and controls ensures comparability before patient testing.

Proficiency testing results should be reviewed by laboratory leadership; failures require documented investigation.

Internal audits and management reviews support continual improvement under ISO 15189.

Specimen rejection criteria should be documented and applied consistently; rejected specimens require recollection.

Turnaround time monitoring should include preanalytical, analytical, and postanalytical phases.

Antibody screening uses reagent red cells with known antigens; a positive screen requires identification with a panel.

Direct antiglobulin test detects antibody or complement on red cells; indirect antiglobulin test detects antibody in serum.

Immunoassay calibration curves should be validated with appropriate standards; drift affects quantitative results.

Biotin interference can cause falsely low or high results depending on assay format; wash steps and blocking reduce risk.

Heterophile antibody tests for infectious mononucleosis may be falsely negative early in illness; repeat testing improves sensitivity.

Serologic diagnosis of acute infection often requires paired sera showing a fourfold rise in antibody titer.

Autoimmune testing should be guided by clinical suspicion; broad panels increase false-positive results.

Quality control for serology includes positive and negative controls with each run and documented acceptance criteria.

Informed consent requires disclosure of material risks, benefits, alternatives, and the consequences of refusal.

Capacity assessment evaluates understanding, appreciation, reasoning, and expression of choice.

Confidentiality exceptions include patient consent, legal requirements, and serious threats to identifiable others.

Documentation errors should be corrected with a single line, dated and initialed; erasures and backdating are prohibited.

Professional competence includes technical skill, communication, and awareness of scope of practice.

Mandatory reporting of communicable diseases supports public health surveillance and control.

Research ethics require voluntary participation, privacy protection, and review by an ethics committee.

Patient complaints should be handled transparently with investigation and corrective action.

Cardiac output regulation: preload, afterload, and contractility determine stroke volume; heart rate is modulated by autonomic tone.

Renal acid-base regulation: bicarbonate reabsorption and hydrogen ion secretion occur in the proximal tubule; distal tubule secretes hydrogen ions.

Respiratory gas exchange depends on alveolar ventilation, perfusion, and diffusion; ventilation-perfusion mismatch causes hypoxemia.

Pharmacokinetic calculations: loading dose depends on volume of distribution; maintenance dose depends on clearance.

Pathology of inflammation: granulomas form in tuberculosis and sarcoidosis; caseous necrosis is characteristic of tuberculosis.

Neoplasia: oncogenes promote growth, tumor suppressor genes restrain growth; both contribute to carcinogenesis.

Antimicrobial pharmacology: beta-lactamase inhibitors extend beta-lactam activity; aminoglycosides require monitoring for nephrotoxicity and ototoxicity.

Homeostasis: negative feedback maintains stability; positive feedback amplifies changes and is less common.

Crude mortality rate = deaths in a period divided by mid-year population, usually per 100,000.

Infant mortality rate = infant deaths under 1 year per 1,000 live births; it reflects population health and healthcare quality.

Incidence density uses person-time at risk and is useful when follow-up times vary.

Randomized controlled trials reduce confounding through randomization and blinding; intention-to-treat analysis preserves comparability.

Outbreak case definition includes clinical criteria, time, place, and person; it can be refined as the investigation progresses.

Hand hygiene compliance is measured by direct observation or electronic monitoring; feedback improves compliance.

Isolation precautions are discontinued according to pathogen-specific criteria, not simply when symptoms improve.

Vaccine cold-chain monitoring includes temperature logs and data loggers; excursions require assessment of viability.

Urine specific gravity and osmolality differ; osmolality is measured by freezing point depression and is more accurate for concentrating ability.

Urine dipstick leukocyte esterase detects esterases from neutrophils; false positives occur with contamination and false negatives with high glucose or protein.

CSF glucose should be interpreted with concurrent serum glucose; a ratio below 0.4 suggests bacterial meningitis.

Pleural fluid LDH and protein are used in Light's criteria; transudates suggest heart failure or cirrhosis.

Ascitic fluid culture should be inoculated at the bedside into blood culture bottles; delayed processing reduces yield.

Semen analysis should be performed after 2–7 days of abstinence; longer abstinence increases volume but reduces motility.

Stool testing for parasites requires three specimens on separate days for optimal sensitivity.

Synovial fluid should be examined for crystals promptly; urate crystals dissolve with prolonged storage.

Quality control in biochemistry includes calibration verification, reagent lot validation, and review of control results before patient reporting.

Delta checks compare current results with previous values; large changes trigger review for specimen or analytical error.

Critical value thresholds should be defined by the laboratory and communicated to clinicians promptly.

Interference studies should be performed during method validation; common interferents include hemoglobin, bilirubin, and lipids.

Point-of-care glucose meters require validation against laboratory methods and operator competency assessment.

Reference interval transference requires validation when a laboratory adopts a method or population change.

Calculated results such as LDL and eGFR should be flagged when their assumptions are not met.

Traceability and uncertainty of measurement support interpretation of results near clinical decision limits.

Gram stain quality depends on specimen quality and smear thickness; thick smears decolorize poorly.

Culture incubation conditions: most bacteria at 35–37°C in 5% CO2; some require anaerobic or microaerophilic conditions.

Colony morphology, hemolysis, and biochemical tests support identification; molecular methods confirm ambiguous isolates.

Antimicrobial susceptibility breakpoints are updated periodically; laboratories must use current standards.

Viral culture is slow and less sensitive than NAAT; it is used for specific viruses such as HSV and CMV.

Fungal antigen tests (galactomannan, beta-D-glucan) support diagnosis of invasive fungal infection; false positives occur with certain antibiotics and materials.

Parasite concentration techniques (formalin-ethyl acetate) improve recovery of cysts and ova compared with direct smears.

Biosafety practices in microbiology include proper handling of cultures and disinfection of work surfaces.

Peripheral smear morphology: hypochromia and microcytosis suggest iron deficiency or thalassemia; macroovalocytes suggest megaloblastic anemia.

Leukocyte alkaline phosphatase and other special tests are used selectively; flow cytometry characterizes leukemias and lymphomas.

Platelet function testing includes platelet aggregometry and PFA-100; results guide diagnosis of inherited or acquired disorders.

Bone marrow aspirate and biopsy provide complementary information; aspiration samples cells and biopsy assesses architecture.

Blood component selection: irradiated components prevent transfusion-associated graft-versus-host disease in immunocompromised patients.

Leukoreduction reduces febrile nonhemolytic reactions and CMV transmission risk.

Transfusion-transmitted infections are reduced by donor screening and nucleic acid testing.

Patient blood management promotes appropriate transfusion thresholds and alternatives to reduce unnecessary exposure.

Urine pH affects crystal formation and drug excretion; alkaline urine promotes excretion of salicylates and uric acid.

Urine protein dipstick is semiquantitative; quantitative 24-hour protein or protein-to-creatinine ratio is used for monitoring.

CSF cell count should be performed within 1 hour; delayed processing causes cell lysis and inaccurate counts.

Pleural fluid pH and glucose should be measured promptly; anaerobic transport preserves accurate values.

Ascitic fluid total protein and albumin support the serum-ascites albumin gradient calculation.

Semen analysis should be performed in a laboratory with validated methods and quality control.

Stool occult blood testing should avoid dietary and drug interference; immunochemical tests are more specific.

Synovial fluid culture should be performed before antibiotics; Gram stain provides early information.

Fixation time should be recorded; prolonged fixation can impair immunohistochemistry and molecular testing.

Tissue cassettes and blocks must be labeled with unique identifiers; mislabeling is a serious patient safety event.

Microtome section thickness affects staining and interpretation; consistent thickness supports reproducibility.

H&E staining quality control includes checking nuclear and cytoplasmic detail and comparing with previous slides.

Cytology screening requires adequate time and ergonomic conditions; fatigue increases error rates.

Ancillary testing on cytology includes HPV genotyping and molecular markers; results should be interpreted with morphology.

Frozen section interpretation should be correlated with permanent sections; discrepancies are reviewed.

Pathology reports should include specimen type, diagnosis, grade, stage, margins, and ancillary results where applicable.

Spectrophotometer wavelength accuracy can be checked with holmium oxide or didymium filters; deviation affects absorbance readings.

Cuvette path length and material affect absorbance; quartz cuvettes are required for UV measurements.

Automated analyzers should be monitored for carryover with high-concentration samples; wash steps reduce carryover.

Ion-selective electrode results can be affected by sample dilution and matrix effects; direct and indirect methods differ.

Pipette tips should match the pipette and be replaced regularly; worn tips cause inaccurate volumes.

Centrifuge tubes must be balanced by weight; imbalance causes vibration and damage.

pH meters require storage in appropriate solution and periodic electrode replacement.

Microscope bulbs should be replaced with the specified type; incorrect bulbs affect color temperature and illumination.

QC rules should be selected based on the analyte's clinical significance and the method's performance.

Control results outside limits require investigation before patient results are reported.

Documented corrective actions should address root cause and prevent recurrence.

Proficiency testing performance should be reviewed by laboratory leadership and used for improvement.

Personnel competency assessment should include direct observation and review of results.

Equipment maintenance records should include dates, actions, and personnel; records support traceability.

Specimen rejection criteria should be based on stability and collection requirements.

Turnaround time should be monitored by phase to identify bottlenecks.

Antibody identification uses panel cells and enzyme-treated cells to characterize specificity.

Direct antiglobulin test positivity indicates immune-mediated red cell destruction or recent transfusion.

Immunoassay interference from heterophile antibodies can be reduced with blocking reagents.

Biotin interference depends on assay format; streptavidin-biotin systems are vulnerable.

Serologic testing for acute infection may require paired sera and a fourfold titer rise.

Autoimmune panels should be ordered selectively to reduce false positives.

Quality control in serology includes positive and negative controls and documented acceptance criteria.

Point-of-care serology requires confirmation of positive results with laboratory methods.

Informed consent should be obtained before invasive procedures and documented in the record.

Capacity assessment considers understanding, appreciation, reasoning, and expression of choice.

Confidentiality may be breached when required by law or when a serious threat exists to an identifiable person.

Documentation errors should be corrected with a dated, initialed line; erasures are prohibited.

Professional competence includes technical skill, communication, and awareness of scope of practice.

Mandatory reporting supports public health surveillance and control.

Research ethics require voluntary participation, privacy protection, and ethics committee review.

Patient complaints should be investigated and resolved transparently.

Cardiac output is determined by heart rate and stroke volume; preload, afterload, and contractility affect stroke volume.

Renal bicarbonate handling maintains acid-base balance; proximal tubule reabsorption is a major mechanism.

Respiratory gas exchange depends on ventilation, perfusion, and diffusion; mismatch causes hypoxemia.

Loading dose depends on volume of distribution; maintenance dose depends on clearance.

Granulomatous inflammation is associated with tuberculosis and sarcoidosis; caseous necrosis is typical of tuberculosis.

Oncogenes promote growth and tumor suppressor genes restrain growth; both contribute to carcinogenesis.

Beta-lactamase inhibitors extend beta-lactam activity; aminoglycosides require monitoring for toxicity.

Negative feedback maintains homeostasis; positive feedback amplifies changes.

Crude mortality rate = deaths in a period divided by mid-year population, usually per 100,000.

Infant mortality rate = infant deaths under 1 year per 1,000 live births.

Incidence density uses person-time at risk and is useful when follow-up times vary.

Randomized controlled trials reduce confounding through randomization and blinding.

Outbreak case definitions include clinical criteria, time, place, and person.

Hand hygiene compliance is measured by observation or electronic monitoring.

Isolation precautions are discontinued according to pathogen-specific criteria.

Vaccine cold-chain monitoring includes temperature logs and data loggers.

Reference intervals are established from a healthy population and should be method- and age-specific.

Critical values in biochemistry include severe hypo- or hyperkalemia, severe hypoglycemia, and marked acidosis.

Enzyme kinetics are measured under zero-order conditions with excess substrate.

Interference from drugs and metabolites can cause false results; delta checks help detect errors.

HbA1c methods must be NGSP-certified; hemoglobin variants alter results.

Lipid testing should follow a 9–12 hour fast when triglycerides are measured.

Tumor markers are used for monitoring, not screening asymptomatic populations.

Traceability of calibrators supports comparability across laboratories.

Sputum is acceptable for culture when many neutrophils and few epithelial cells are seen.

Anaerobic culture requires prompt transport in anaerobic containers.

Mycoplasma and Chlamydia require molecular methods for detection.

Viral load assays quantify nucleic acid and monitor treatment response.

Fungal identification combines colony morphology, microscopy, and biochemical or molecular tests.

Giardia antigen testing is more sensitive than microscopy.

Biosafety cabinets are used for aerosol-generating procedures.

Antimicrobial susceptibility reporting should follow current breakpoints.

Low reticulocyte count suggests a production defect; high count suggests destruction or blood loss.

Microcytic anemia differential includes iron deficiency, thalassemia, and anemia of chronic disease.

Megaloblastic anemia shows oval macrocytes and hypersegmented neutrophils.

Hemolytic anemia markers include raised reticulocytes, indirect bilirubin, and LDH with low haptoglobin.

Mixing study corrects in factor deficiency and fails to correct with an inhibitor.

Clinically significant antibodies include Rh, Kell, Duffy, and Kidd.

Transfusion reaction workup includes clerical check, repeat ABO typing, and direct antiglobulin test.

Bedside patient identification is the most important safeguard against wrong-blood transfusion.

Urine reagent strips should be read at the specified time; delayed reading causes false positives.

Urine protein-to-creatinine ratio estimates 24-hour protein excretion.

CSF bacterial antigen testing is less sensitive than culture and NAAT.

Pleural fluid is sent for cell count, protein, LDH, glucose, pH, cytology, and culture.

Ascitic fluid should be inoculated into blood culture bottles at the bedside.

Semen reference limits are based on the lower fifth percentile of fertile men.

Stool culture and parasite examination require appropriate transport media.

Synovial fluid cell count and differential distinguish inflammatory from noninflammatory disease.

Formalin cross-links proteins and preserves architecture; antigen retrieval reverses some cross-linking.

Paraffin embedding requires complete dehydration and clearing.

Microtome blade angle and clearance angle affect section quality.

H&E differentiation: excess hematoxylin causes overstaining; acid alcohol removes excess dye.

Cytology specimens include exfoliative and aspiration samples with specific processing requirements.

Immunocytochemistry on cytology requires validated protocols and controls.

TNM staging is more predictive of prognosis than grading.

Cytology quality control includes screening limits and rescreening of negative cases.

Spectrophotometer linearity should be verified with calibrated filters or standards.

Stray light limits the upper absorbance range and should be checked.

Ion-selective electrodes require daily calibration and periodic membrane replacement.

Automated analyzers use liquid-level sensing to detect clogged probes.

Pipette accuracy and precision should be checked at the intended volume.

Centrifuge speed should be verified with a tachometer.

pH meter calibration should use fresh buffers and temperature compensation.

Microscope numerical aperture and condenser alignment determine resolution.

QC frequency should be based on method stability and clinical risk.

Patient-based QC using delta checks and moving averages detects errors between control runs.

Recalibration is required after major maintenance or reagent lot change.

Lot-to-lot verification ensures comparability before patient testing.

Proficiency testing failures require documented investigation.

Internal audits and management reviews support continual improvement.

Specimen rejection criteria should be documented and applied consistently.

Turnaround time monitoring should include preanalytical, analytical, and postanalytical phases.

Antibody screening uses reagent red cells with known antigens.

Direct antiglobulin test detects antibody or complement on red cells.

Immunoassay calibration curves should be validated with appropriate standards.

Biotin interference depends on assay format and can be reduced with blocking reagents.

Heterophile antibody tests may be falsely negative early in illness.

Paired sera showing a fourfold rise support acute infection diagnosis.

Autoimmune testing should be guided by clinical suspicion.

Serology quality control includes positive and negative controls with acceptance criteria.

Informed consent requires disclosure of material risks, benefits, alternatives, and consequences of refusal.

Capacity assessment evaluates understanding, appreciation, reasoning, and expression of choice.

Confidentiality exceptions include consent, legal requirements, and serious threats to identifiable others.

Documentation errors should be corrected with a single line, dated and initialed.

Professional competence includes technical skill, communication, and scope of practice awareness.

Mandatory reporting of communicable diseases supports public health surveillance.

Research ethics require voluntary participation and ethics committee review.

Patient complaints should be investigated and resolved transparently.

Preload, afterload, and contractility determine stroke volume.

Renal bicarbonate reabsorption and hydrogen ion secretion maintain acid-base balance.

Ventilation-perfusion mismatch causes hypoxemia.

Loading dose depends on volume of distribution; maintenance dose depends on clearance.

Granulomas form in tuberculosis and sarcoidosis; caseous necrosis is typical of tuberculosis.

Oncogenes promote growth and tumor suppressor genes restrain growth.

Beta-lactamase inhibitors extend beta-lactam activity.

Negative feedback maintains homeostasis; positive feedback amplifies changes.

Crude mortality rate uses mid-year population as the denominator.

Infant mortality rate reflects population health and healthcare quality.

Incidence density uses person-time at risk.

Randomized controlled trials reduce confounding through randomization and blinding.

Outbreak case definitions include clinical criteria, time, place, and person.

Hand hygiene compliance is measured by observation or electronic monitoring.

Isolation precautions are discontinued according to pathogen-specific criteria.

Vaccine cold-chain monitoring includes temperature logs and data loggers.

Urine osmolality measured by freezing point depression is more accurate than specific gravity for concentrating ability.

Leukocyte esterase detects neutrophil esterases; false positives occur with contamination.

CSF glucose ratio below 0.4 suggests bacterial meningitis.

Light's criteria use pleural fluid and serum protein and LDH ratios.

Ascitic fluid culture yield improves with bedside inoculation into blood culture bottles.

Semen analysis after 2–7 days of abstinence is standard.

Three stool specimens on separate days improve parasite detection.

Urate crystals dissolve with prolonged storage; examine synovial fluid promptly.