NHPC BMLT flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Beer-Lambert law

Absorbance is directly proportional to analyte concentration, path length, and molar absorptivity. Spectrophotometric assays are valid only within the validated linear range.

Westgard 1-3s rule

A control result exceeding ±3 SD from the mean rejects the analytical run. It detects random error and is one of the most widely applied multirule criteria.

Anion gap

Calculated as sodium minus the sum of chloride and bicarbonate, normally 8–12 mmol/L. A raised gap with metabolic acidosis suggests ketoacidosis, lactate, uremia, or toxins.

HbA1c

Glycated hemoglobin reflecting average glucose over about 120 days, the red cell lifespan. Values of 6.5% or higher support a diagnosis of diabetes when confirmed.

Coagulase test

Detects the enzyme coagulase produced by Staphylococcus aureus, which converts fibrinogen to fibrin. It distinguishes S. aureus from coagulase-negative staphylococci.

MacConkey agar

Selective and differential medium containing bile salts and lactose. Gram-negative lactose fermenters form pink colonies, while non-fermenters remain colorless.

Germ tube test

Incubation of yeast in serum at 37°C for about two hours; Candida albicans forms tube-like projections. It is a rapid presumptive identification test.

Direct antiglobulin test

Detects antibody or complement bound to red cells using anti-human globulin. It is used in hemolytic disease of the newborn and suspected transfusion reactions.

Universal donor red cells

Group O red cells lack A and B antigens and can be given to recipients of any ABO group. Group AB plasma is the corresponding universal plasma donor.

Light's criteria

Pleural fluid is an exudate when protein ratio exceeds 0.5, LDH ratio exceeds 0.6, or fluid LDH exceeds two-thirds the upper normal serum LDH.

Serum-ascites albumin gradient

Serum albumin minus ascitic albumin; a gradient of 1.1 g/dL or more indicates portal hypertension, while lower values suggest peritoneal disease.

Hematoxylin and eosin

Routine histology stain in which basic hematoxylin stains nuclei blue-purple and acidic eosin stains cytoplasm and collagen pink.

Frozen section

Rapid intraoperative tissue preparation using a cryostat. It is used for margin assessment and tissue triage but is less precise than paraffin sections.

Ion-selective electrode

Potentiometric sensor that measures electrolyte activity through a selective membrane. Indirect methods dilute the sample and can be affected by hyperlipidemia.

Levey-Jennings chart

Graph plotting control values over time against mean and standard deviation limits. Shifts indicate systematic error, while trends indicate gradual drift.

External quality assessment

Proficiency testing in which unknown samples are analyzed and compared with peer laboratories. Unacceptable performance requires investigation and corrective action.

IgM antibody

Pentameric immunoglobulin produced early in primary infection. It is too large to cross the placenta and indicates recent or acute exposure in serology.

Prozone phenomenon

False-negative agglutination caused by antibody excess. Diluting the serum restores the optimal antigen-antibody ratio and reveals the reaction.

Informed consent

Voluntary agreement after disclosure of material risks, benefits, alternatives, and consequences of refusal. The patient must have capacity and understand the information.

Medical negligence

A claim requires duty of care, breach of the standard of care, causation, and damages. Documentation and expert testimony are central to the defense.

Cardiac output

Product of heart rate and stroke volume. Stroke volume is influenced by preload, afterload, and contractility, and blood pressure equals output times resistance.

Apoptosis

Energy-dependent, caspase-mediated programmed cell death with cell shrinkage and membrane blebbing. Unlike necrosis, it does not provoke inflammation.

Herd immunity

Indirect protection of unvaccinated individuals when sufficient coverage interrupts transmission. The threshold rises with the pathogen's basic reproduction number.

Standard precautions

Infection control practices applied to all patients, including hand hygiene, gloves, gowns, and safe sharps handling, regardless of suspected diagnosis.

Incidence versus prevalence

Incidence counts new cases over a period; prevalence counts all existing cases at a point. Prevalence approximates incidence multiplied by disease duration.

Transferrin saturation

Serum iron divided by total iron-binding capacity, expressed as a percentage. Low saturation with low ferritin supports iron deficiency anemia.

Reticulocyte production index

Corrected reticulocyte percentage adjusted for anemia severity and maturation time. It distinguishes hypoproliferative from hemolytic or blood-loss anemia.

CSF glucose ratio

Cerebrospinal fluid glucose divided by simultaneous serum glucose. A ratio below about 0.4 suggests bacterial meningitis or other causes of low CSF glucose.

Bethesda system

Standardized cervical cytology reporting categories ranging from NILM through ASC-US, LSIL, HSIL, and carcinoma, guiding colposcopy and follow-up.

Relative centrifugal force

Calculated as 1.118 × 10⁻⁵ times rotor radius in centimeters times RPM squared. It standardizes centrifugation conditions across different centrifuges.

Affinity versus avidity

Affinity is the strength of a single antigen-antibody binding site; avidity is the overall strength of multivalent binding. Both influence immunoassay performance.

Duty to warn

An exception to confidentiality permitting disclosure when a patient poses a serious threat to an identifiable third party, as defined by law.

Therapeutic index

Ratio of toxic dose to effective dose. A narrow index requires therapeutic drug monitoring and careful dosing to avoid toxicity.