CLIA CCC cheat sheet

Anion gap = Na − (Cl + HCO3); reference ~8–12 mmol/L; elevated gap suggests MUDPILES (methanol, uremia, DKA, propylene glycol, isoniazid, lactic acidosis, ethylene glycol, salicylates).

Osmolal gap = measured osmolality − calculated (2Na + glucose/18 + BUN/2.8); gap >10 suggests unmeasured osmoles such as methanol or ethylene glycol.

Friedewald LDL = TC − HDL − (TG/5), valid only when TG <400 mg/dL; use direct LDL or non-HDL when TG exceeds this.

Corrected calcium (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL); ionized calcium is unaffected by albumin.

Enzymatic creatinine methods are subject to negative interference from high bilirubin and positive interference from ketoacids; Jaffe methods are less specific.

Cardiac troponin I and T rise 3–6 h after injury, peak ~12–24 h, and remain elevated for 5–14 days; CK-MB normalizes in 2–3 days.

HbA1c reflects mean glucose over ~90–120 days (RBC lifespan); NGSP-certified methods must be used, and hemoglobin variants can interfere with some assays.

Delta checks flag a result that differs from the patient's prior value by more than a set threshold; they are a key autoverification safety rule.

MCV = (Hct × 10)/RBC (fL); MCH = Hgb/RBC × 10 (pg); MCHC = Hgb/Hct × 100 (g/dL); MCHC >36 suggests spherocytosis, lipemia, or cold agglutinin artifact.

RDW-CV >14.5% indicates anisocytosis; a high RDW with low MCV favors iron deficiency over thalassemia trait.

Corrected WBC = observed WBC × (100 / (100 + nucleated RBCs per 100 WBC)); failure to correct causes falsely elevated counts in newborns.

Reticulocyte index = reticulocyte % × (patient Hct / normal Hct) ÷ maturation factor (~2 for Hct <25%); index >2 indicates adequate marrow response.

PT measures extrinsic/common pathway (factors VII, X, V, II, fibrinogen); aPTT measures intrinsic/common (VIII, IX, XI, XII, X, V, II, fibrinogen).

Mixing study: correction of a prolonged aPTT immediately after 1:1 mixing suggests factor deficiency; failure to correct suggests an inhibitor such as lupus anticoagulant or factor VIII inhibitor.

D-dimer has high sensitivity but low specificity for VTE; a negative result with low pretest probability supports exclusion of pulmonary embolism.

G6PD deficiency shows bite cells and Heinz bodies; do not transfuse or test during acute hemolysis because reticulocytes and young RBCs have higher enzyme levels.

Staphylococcus aureus: catalase positive, coagulase positive, grows in 6.5% NaCl; streptococci are catalase negative.

Lancefield grouping: group A = S. pyogenes (bacitracin susceptible), group B = S. agalactiae (hippurate positive, CAMP positive).

Enterobacteriaceae are oxidase negative, glucose fermenters, and reduce nitrate; Pseudomonas aeruginosa is oxidase positive and non-fermentative.

Blood culture bottles should be incubated at 35–37 °C and routinely held 5 days; organisms such as Brucella and HACEK require extended incubation.

CSF bacterial meningitis typical profile: elevated WBC with neutrophil predominance, high protein, low glucose (<40 mg/dL or CSF/serum ratio <0.4).

MRSA is confirmed by cefoxitin disk or oxacillin/mecA PCR; inducible clindamycin resistance is detected with the D-test.

Carbapenemase-producing organisms are screened by carbapenem MIC or disk diffusion and confirmed by PCR or phenotypic tests such as mCIM.

Urine culture colony count ≥10^5 CFU/mL of a single organism is significant in clean-catch specimens; mixed flora suggests contamination.

ABO: A has A antigen and anti-B; B has B antigen and anti-A; AB has both antigens and no antibodies; O has no antigens and both anti-A and anti-B.

Forward and reverse ABO grouping must agree; a discrepancy requires resolution before transfusion (e.g., weak subgroups, cold autoantibody, or missing reverse reaction in newborns).

Rh(D) negative patients receive D-negative RBCs; weak D testing determines whether a donor unit is labeled D positive or negative.

Antibody screen positive requires identification by panel cells; clinically significant antibodies (e.g., anti-Jka, anti-K, anti-Fya) require antigen-negative units.

Crossmatch: immediate spin detects ABO incompatibility; AHG phase detects IgG antibodies; computer crossmatch is allowed only when the antibody screen is negative and historical records agree.

RBC units stored at 1–6 °C; expiration depends on additive: AS-1/AS-3 = 42 days, CPDA-1 = 35 days, and CPD/CP2D = 21 days.

Platelets stored at 20–24 °C with continuous agitation for 5 days; never refrigerate platelets.

Transfusion reaction: stop transfusion immediately, keep IV line open with saline, and return the bag and tubing with post-transfusion samples for investigation.

Sensitivity = TP/(TP + FN); specificity = TN/(TN + FP); positive predictive value depends on disease prevalence.

ELISA: direct detects antigen, indirect detects antibody; sandwich ELISA is highly sensitive for antigen detection.

Western blot is used as a confirmatory test (e.g., HIV, Lyme); interpretation requires detection of specific bands, not just any band.

ANA by IFA: homogeneous pattern suggests anti-dsDNA or anti-histone; speckled suggests anti-Sm, anti-RNP, or anti-SSA/SSB.

Anti-dsDNA and anti-Sm are specific for SLE; anti-histone is associated with drug-induced lupus.

Rheumatoid factor is an IgM antibody against IgG Fc; anti-CCP is more specific for rheumatoid arthritis.

Complement: C3 and C4 decrease in active SLE and in immune-complex disease; CH50 measures the classical pathway.

Syphilis serology: nontreponemal tests (RPR, VDRL) are used for screening and monitoring; treponemal tests (FTA-ABS, TP-PA) confirm and remain positive for life.

Urine specific gravity by reagent strip reflects ionic concentration and is affected by pH; refractometry measures all solutes.

Reagent strip protein is most sensitive to albumin; a positive result at low pH can be a false positive from high specific gravity or alkaline urine.

Leukocyte esterase detects esterases from neutrophils; nitrite positivity indicates nitrate-reducing organisms such as Enterobacteriaceae.

Hyaline casts are normal; RBC casts indicate glomerular bleeding; WBC casts suggest pyelonephritis; waxy casts indicate chronic renal failure.

Urine pH >7.5 with positive nitrite and leukocyte esterase supports urinary tract infection; alkaline urine can also cause false-positive protein.

Synovial fluid: normal is clear, viscous, WBC <200/µL; septic fluid is turbid, low viscosity, WBC >50,000/µL with neutrophil predominance.

CSF glucose should be about 60% of serum glucose; values <40 mg/dL or a ratio <0.4 suggest bacterial or fungal meningitis.

Semen analysis reference: volume ≥1.5 mL, concentration ≥15 million/mL, total motility ≥40%, normal morphology ≥4% (WHO 2010).

PCR requires a thermostable DNA polymerase, primers, dNTPs, Mg2+, and template; each cycle doubles the target in exponential phase.

Real-time PCR quantifies product by fluorescence; Ct value is inversely proportional to starting template concentration.

Sanger sequencing is the gold standard for single-gene confirmation; next-generation sequencing provides high throughput but requires bioinformatics validation.

Karyotype resolution is ~5–10 Mb; FISH detects specific loci with ~100–200 kb resolution; microarray detects copy-number changes at kilobase resolution.

Common translocations: t(9;22) BCR-ABL in CML; t(15;17) PML-RARA in APL; t(8;21) RUNX1-RUNX1T1 in AML.

Turner syndrome is 45,X; Klinefelter is 47,XXY; Down syndrome is trisomy 21, most often from maternal nondisjunction.

Molecular testing must include positive and negative controls per run, and contamination controls such as no-template controls.

Levey-Jennings chart: results within ±2 SD are acceptable; a single result beyond ±3 SD or two consecutive beyond ±2 SD on one side is a rejection rule.

Westgard rules: 1-3s (reject), 2-2s (reject), R-4s (reject), 4-1s (reject), 10x (reject); 1-2s is a warning.

Coefficient of variation (CV) = (SD/mean) × 100; lower CV indicates better precision.

Standard precautions require gloves for all blood and body fluid contact; PPE selection depends on task and exposure risk.

Chemical spills: use the SDS for hazard information, contain the spill, and use appropriate absorbent; mercury spills require special cleanup.

Fire safety: PASS = Pull, Aim, Squeeze, Sweep; use a Class C extinguisher for electrical fires.

Biological spill cleanup: absorb, apply disinfectant (e.g., 1:10 bleach), allow contact time, and dispose as biohazardous waste.

Proficiency testing (PT) must be performed like patient samples; unacceptable PT results require investigation and corrective action.

CLIA complexity categories: waived, moderate complexity, and high complexity; the laboratory's certificate must match the testing performed.

A Certificate of Waiver permits only waived tests; a Certificate of Compliance or Accreditation is required for moderate- and high-complexity testing.

Moderate-complexity labs must have a laboratory director, technical consultant, and general supervisor; high-complexity labs also require a technical supervisor.

Personnel qualifications: high-complexity testing requires a director with a doctoral degree and appropriate experience; technologists need specified education and experience.

Quality assessment (QA) must include preanalytic, analytic, and postanalytic monitoring, plus review of proficiency testing and patient complaints.

Proficiency testing is required for regulated analytes; alternative assessment is allowed for unregulated analytes.

CLIA requires biennial inspection (or accreditation survey) and a current certificate; changes in ownership or location require notification.

Record retention: patient test records generally 2 years; quality control and proficiency records 2 years; some states require longer.

Anion gap = Na − (Cl + HCO3); reference ~8–12 mmol/L; elevated gap suggests MUDPILES (methanol, uremia, DKA, propylene glycol, isoniazid, lactic acidosis, ethylene glycol, salicylates).

Osmolal gap = measured osmolality − calculated (2Na + glucose/18 + BUN/2.8); gap >10 suggests unmeasured osmoles such as methanol or ethylene glycol.

Friedewald LDL = TC − HDL − (TG/5), valid only when TG <400 mg/dL; use direct LDL or non-HDL when TG exceeds this.

Corrected calcium (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL); ionized calcium is unaffected by albumin.

Enzymatic creatinine methods are subject to negative interference from high bilirubin and positive interference from ketoacids; Jaffe methods are less specific.

Cardiac troponin I and T rise 3–6 h after injury, peak ~12–24 h, and remain elevated for 5–14 days; CK-MB normalizes in 2–3 days.

HbA1c reflects mean glucose over ~90–120 days (RBC lifespan); NGSP-certified methods must be used, and hemoglobin variants can interfere with some assays.

Delta checks flag a result that differs from the patient's prior value by more than a set threshold; they are a key autoverification safety rule.

MCV = (Hct × 10)/RBC (fL); MCH = Hgb/RBC × 10 (pg); MCHC = Hgb/Hct × 100 (g/dL); MCHC >36 suggests spherocytosis, lipemia, or cold agglutinin artifact.

RDW-CV >14.5% indicates anisocytosis; a high RDW with low MCV favors iron deficiency over thalassemia trait.

Corrected WBC = observed WBC × (100 / (100 + nucleated RBCs per 100 WBC)); failure to correct causes falsely elevated counts in newborns.

Reticulocyte index = reticulocyte % × (patient Hct / normal Hct) ÷ maturation factor (~2 for Hct <25%); index >2 indicates adequate marrow response.

PT measures extrinsic/common pathway (factors VII, X, V, II, fibrinogen); aPTT measures intrinsic/common (VIII, IX, XI, XII, X, V, II, fibrinogen).

Mixing study: correction of a prolonged aPTT immediately after 1:1 mixing suggests factor deficiency; failure to correct suggests an inhibitor such as lupus anticoagulant or factor VIII inhibitor.

D-dimer has high sensitivity but low specificity for VTE; a negative result with low pretest probability supports exclusion of pulmonary embolism.

G6PD deficiency shows bite cells and Heinz bodies; do not transfuse or test during acute hemolysis because reticulocytes and young RBCs have higher enzyme levels.

Staphylococcus aureus: catalase positive, coagulase positive, grows in 6.5% NaCl; streptococci are catalase negative.

Lancefield grouping: group A = S. pyogenes (bacitracin susceptible), group B = S. agalactiae (hippurate positive, CAMP positive).

Enterobacteriaceae are oxidase negative, glucose fermenters, and reduce nitrate; Pseudomonas aeruginosa is oxidase positive and non-fermentative.

Blood culture bottles should be incubated at 35–37 °C and routinely held 5 days; organisms such as Brucella and HACEK require extended incubation.

CSF bacterial meningitis typical profile: elevated WBC with neutrophil predominance, high protein, low glucose (<40 mg/dL or CSF/serum ratio <0.4).

MRSA is confirmed by cefoxitin disk or oxacillin/mecA PCR; inducible clindamycin resistance is detected with the D-test.

Carbapenemase-producing organisms are screened by carbapenem MIC or disk diffusion and confirmed by PCR or phenotypic tests such as mCIM.

Urine culture colony count ≥10^5 CFU/mL of a single organism is significant in clean-catch specimens; mixed flora suggests contamination.

ABO: A has A antigen and anti-B; B has B antigen and anti-A; AB has both antigens and no antibodies; O has no antigens and both anti-A and anti-B.

Forward and reverse ABO grouping must agree; a discrepancy requires resolution before transfusion (e.g., weak subgroups, cold autoantibody, or missing reverse reaction in newborns).

Rh(D) negative patients receive D-negative RBCs; weak D testing determines whether a donor unit is labeled D positive or negative.

Antibody screen positive requires identification by panel cells; clinically significant antibodies (e.g., anti-Jka, anti-K, anti-Fya) require antigen-negative units.

Crossmatch: immediate spin detects ABO incompatibility; AHG phase detects IgG antibodies; computer crossmatch is allowed only when the antibody screen is negative and historical records agree.

RBC units stored at 1–6 °C; expiration depends on additive: AS-1/AS-3 = 42 days, CPDA-1 = 35 days, and CPD/CP2D = 21 days.

Platelets stored at 20–24 °C with continuous agitation for 5 days; never refrigerate platelets.

Transfusion reaction: stop transfusion immediately, keep IV line open with saline, and return the bag and tubing with post-transfusion samples for investigation.

Sensitivity = TP/(TP + FN); specificity = TN/(TN + FP); positive predictive value depends on disease prevalence.

ELISA: direct detects antigen, indirect detects antibody; sandwich ELISA is highly sensitive for antigen detection.

Western blot is used as a confirmatory test (e.g., HIV, Lyme); interpretation requires detection of specific bands, not just any band.

ANA by IFA: homogeneous pattern suggests anti-dsDNA or anti-histone; speckled suggests anti-Sm, anti-RNP, or anti-SSA/SSB.

Anti-dsDNA and anti-Sm are specific for SLE; anti-histone is associated with drug-induced lupus.

Rheumatoid factor is an IgM antibody against IgG Fc; anti-CCP is more specific for rheumatoid arthritis.

Complement: C3 and C4 decrease in active SLE and in immune-complex disease; CH50 measures the classical pathway.

Syphilis serology: nontreponemal tests (RPR, VDRL) are used for screening and monitoring; treponemal tests (FTA-ABS, TP-PA) confirm and remain positive for life.

Urine specific gravity by reagent strip reflects ionic concentration and is affected by pH; refractometry measures all solutes.

Reagent strip protein is most sensitive to albumin; a positive result at low pH can be a false positive from high specific gravity or alkaline urine.

Leukocyte esterase detects esterases from neutrophils; nitrite positivity indicates nitrate-reducing organisms such as Enterobacteriaceae.

Hyaline casts are normal; RBC casts indicate glomerular bleeding; WBC casts suggest pyelonephritis; waxy casts indicate chronic renal failure.

Urine pH >7.5 with positive nitrite and leukocyte esterase supports urinary tract infection; alkaline urine can also cause false-positive protein.

Synovial fluid: normal is clear, viscous, WBC <200/µL; septic fluid is turbid, low viscosity, WBC >50,000/µL with neutrophil predominance.

CSF glucose should be about 60% of serum glucose; values <40 mg/dL or a ratio <0.4 suggest bacterial or fungal meningitis.

Semen analysis reference: volume ≥1.5 mL, concentration ≥15 million/mL, total motility ≥40%, normal morphology ≥4% (WHO 2010).

PCR requires a thermostable DNA polymerase, primers, dNTPs, Mg2+, and template; each cycle doubles the target in exponential phase.

Real-time PCR quantifies product by fluorescence; Ct value is inversely proportional to starting template concentration.

Sanger sequencing is the gold standard for single-gene confirmation; next-generation sequencing provides high throughput but requires bioinformatics validation.

Karyotype resolution is ~5–10 Mb; FISH detects specific loci with ~100–200 kb resolution; microarray detects copy-number changes at kilobase resolution.

Common translocations: t(9;22) BCR-ABL in CML; t(15;17) PML-RARA in APL; t(8;21) RUNX1-RUNX1T1 in AML.

Turner syndrome is 45,X; Klinefelter is 47,XXY; Down syndrome is trisomy 21, most often from maternal nondisjunction.

Molecular testing must include positive and negative controls per run, and contamination controls such as no-template controls.

Levey-Jennings chart: results within ±2 SD are acceptable; a single result beyond ±3 SD or two consecutive beyond ±2 SD on one side is a rejection rule.

Westgard rules: 1-3s (reject), 2-2s (reject), R-4s (reject), 4-1s (reject), 10x (reject); 1-2s is a warning.

Coefficient of variation (CV) = (SD/mean) × 100; lower CV indicates better precision.

Standard precautions require gloves for all blood and body fluid contact; PPE selection depends on task and exposure risk.

Chemical spills: use the SDS for hazard information, contain the spill, and use appropriate absorbent; mercury spills require special cleanup.

Fire safety: PASS = Pull, Aim, Squeeze, Sweep; use a Class C extinguisher for electrical fires.

Biological spill cleanup: absorb, apply disinfectant (e.g., 1:10 bleach), allow contact time, and dispose as biohazardous waste.

Proficiency testing (PT) must be performed like patient samples; unacceptable PT results require investigation and corrective action.

CLIA complexity categories: waived, moderate complexity, and high complexity; the laboratory's certificate must match the testing performed.

A Certificate of Waiver permits only waived tests; a Certificate of Compliance or Accreditation is required for moderate- and high-complexity testing.

Moderate-complexity labs must have a laboratory director, technical consultant, and general supervisor; high-complexity labs also require a technical supervisor.

Personnel qualifications: high-complexity testing requires a director with a doctoral degree and appropriate experience; technologists need specified education and experience.

Quality assessment (QA) must include preanalytic, analytic, and postanalytic monitoring, plus review of proficiency testing and patient complaints.

Proficiency testing is required for regulated analytes; alternative assessment is allowed for unregulated analytes.

CLIA requires biennial inspection (or accreditation survey) and a current certificate; changes in ownership or location require notification.

Record retention: patient test records generally 2 years; quality control and proficiency records 2 years; some states require longer.

Anion gap = Na − (Cl + HCO3); reference ~8–12 mmol/L; elevated gap suggests MUDPILES (methanol, uremia, DKA, propylene glycol, isoniazid, lactic acidosis, ethylene glycol, salicylates).

Osmolal gap = measured osmolality − calculated (2Na + glucose/18 + BUN/2.8); gap >10 suggests unmeasured osmoles such as methanol or ethylene glycol.

Friedewald LDL = TC − HDL − (TG/5), valid only when TG <400 mg/dL; use direct LDL or non-HDL when TG exceeds this.

Corrected calcium (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL); ionized calcium is unaffected by albumin.

Enzymatic creatinine methods are subject to negative interference from high bilirubin and positive interference from ketoacids; Jaffe methods are less specific.

Cardiac troponin I and T rise 3–6 h after injury, peak ~12–24 h, and remain elevated for 5–14 days; CK-MB normalizes in 2–3 days.

HbA1c reflects mean glucose over ~90–120 days (RBC lifespan); NGSP-certified methods must be used, and hemoglobin variants can interfere with some assays.

Delta checks flag a result that differs from the patient's prior value by more than a set threshold; they are a key autoverification safety rule.

MCV = (Hct × 10)/RBC (fL); MCH = Hgb/RBC × 10 (pg); MCHC = Hgb/Hct × 100 (g/dL); MCHC >36 suggests spherocytosis, lipemia, or cold agglutinin artifact.

RDW-CV >14.5% indicates anisocytosis; a high RDW with low MCV favors iron deficiency over thalassemia trait.

Corrected WBC = observed WBC × (100 / (100 + nucleated RBCs per 100 WBC)); failure to correct causes falsely elevated counts in newborns.

Reticulocyte index = reticulocyte % × (patient Hct / normal Hct) ÷ maturation factor (~2 for Hct <25%); index >2 indicates adequate marrow response.

PT measures extrinsic/common pathway (factors VII, X, V, II, fibrinogen); aPTT measures intrinsic/common (VIII, IX, XI, XII, X, V, II, fibrinogen).

Mixing study: correction of a prolonged aPTT immediately after 1:1 mixing suggests factor deficiency; failure to correct suggests an inhibitor such as lupus anticoagulant or factor VIII inhibitor.

D-dimer has high sensitivity but low specificity for VTE; a negative result with low pretest probability supports exclusion of pulmonary embolism.

G6PD deficiency shows bite cells and Heinz bodies; do not transfuse or test during acute hemolysis because reticulocytes and young RBCs have higher enzyme levels.

Staphylococcus aureus: catalase positive, coagulase positive, grows in 6.5% NaCl; streptococci are catalase negative.

Lancefield grouping: group A = S. pyogenes (bacitracin susceptible), group B = S. agalactiae (hippurate positive, CAMP positive).

Enterobacteriaceae are oxidase negative, glucose fermenters, and reduce nitrate; Pseudomonas aeruginosa is oxidase positive and non-fermentative.

Blood culture bottles should be incubated at 35–37 °C and routinely held 5 days; organisms such as Brucella and HACEK require extended incubation.

CSF bacterial meningitis typical profile: elevated WBC with neutrophil predominance, high protein, low glucose (<40 mg/dL or CSF/serum ratio <0.4).

MRSA is confirmed by cefoxitin disk or oxacillin/mecA PCR; inducible clindamycin resistance is detected with the D-test.

Carbapenemase-producing organisms are screened by carbapenem MIC or disk diffusion and confirmed by PCR or phenotypic tests such as mCIM.

Urine culture colony count ≥10^5 CFU/mL of a single organism is significant in clean-catch specimens; mixed flora suggests contamination.

ABO: A has A antigen and anti-B; B has B antigen and anti-A; AB has both antigens and no antibodies; O has no antigens and both anti-A and anti-B.

Forward and reverse ABO grouping must agree; a discrepancy requires resolution before transfusion (e.g., weak subgroups, cold autoantibody, or missing reverse reaction in newborns).

Rh(D) negative patients receive D-negative RBCs; weak D testing determines whether a donor unit is labeled D positive or negative.

Antibody screen positive requires identification by panel cells; clinically significant antibodies (e.g., anti-Jka, anti-K, anti-Fya) require antigen-negative units.

Crossmatch: immediate spin detects ABO incompatibility; AHG phase detects IgG antibodies; computer crossmatch is allowed only when the antibody screen is negative and historical records agree.

RBC units stored at 1–6 °C; expiration depends on additive: AS-1/AS-3 = 42 days, CPDA-1 = 35 days, and CPD/CP2D = 21 days.

Platelets stored at 20–24 °C with continuous agitation for 5 days; never refrigerate platelets.

Transfusion reaction: stop transfusion immediately, keep IV line open with saline, and return the bag and tubing with post-transfusion samples for investigation.

Sensitivity = TP/(TP + FN); specificity = TN/(TN + FP); positive predictive value depends on disease prevalence.

ELISA: direct detects antigen, indirect detects antibody; sandwich ELISA is highly sensitive for antigen detection.

Western blot is used as a confirmatory test (e.g., HIV, Lyme); interpretation requires detection of specific bands, not just any band.

ANA by IFA: homogeneous pattern suggests anti-dsDNA or anti-histone; speckled suggests anti-Sm, anti-RNP, or anti-SSA/SSB.

Anti-dsDNA and anti-Sm are specific for SLE; anti-histone is associated with drug-induced lupus.

Rheumatoid factor is an IgM antibody against IgG Fc; anti-CCP is more specific for rheumatoid arthritis.

Complement: C3 and C4 decrease in active SLE and in immune-complex disease; CH50 measures the classical pathway.

Syphilis serology: nontreponemal tests (RPR, VDRL) are used for screening and monitoring; treponemal tests (FTA-ABS, TP-PA) confirm and remain positive for life.

Urine specific gravity by reagent strip reflects ionic concentration and is affected by pH; refractometry measures all solutes.

Reagent strip protein is most sensitive to albumin; a positive result at low pH can be a false positive from high specific gravity or alkaline urine.

Leukocyte esterase detects esterases from neutrophils; nitrite positivity indicates nitrate-reducing organisms such as Enterobacteriaceae.

Hyaline casts are normal; RBC casts indicate glomerular bleeding; WBC casts suggest pyelonephritis; waxy casts indicate chronic renal failure.

Urine pH >7.5 with positive nitrite and leukocyte esterase supports urinary tract infection; alkaline urine can also cause false-positive protein.

Synovial fluid: normal is clear, viscous, WBC <200/µL; septic fluid is turbid, low viscosity, WBC >50,000/µL with neutrophil predominance.

CSF glucose should be about 60% of serum glucose; values <40 mg/dL or a ratio <0.4 suggest bacterial or fungal meningitis.

Semen analysis reference: volume ≥1.5 mL, concentration ≥15 million/mL, total motility ≥40%, normal morphology ≥4% (WHO 2010).

PCR requires a thermostable DNA polymerase, primers, dNTPs, Mg2+, and template; each cycle doubles the target in exponential phase.

Real-time PCR quantifies product by fluorescence; Ct value is inversely proportional to starting template concentration.

Sanger sequencing is the gold standard for single-gene confirmation; next-generation sequencing provides high throughput but requires bioinformatics validation.

Karyotype resolution is ~5–10 Mb; FISH detects specific loci with ~100–200 kb resolution; microarray detects copy-number changes at kilobase resolution.

Common translocations: t(9;22) BCR-ABL in CML; t(15;17) PML-RARA in APL; t(8;21) RUNX1-RUNX1T1 in AML.

Turner syndrome is 45,X; Klinefelter is 47,XXY; Down syndrome is trisomy 21, most often from maternal nondisjunction.

Molecular testing must include positive and negative controls per run, and contamination controls such as no-template controls.

Levey-Jennings chart: results within ±2 SD are acceptable; a single result beyond ±3 SD or two consecutive beyond ±2 SD on one side is a rejection rule.

Westgard rules: 1-3s (reject), 2-2s (reject), R-4s (reject), 4-1s (reject), 10x (reject); 1-2s is a warning.

Coefficient of variation (CV) = (SD/mean) × 100; lower CV indicates better precision.

Standard precautions require gloves for all blood and body fluid contact; PPE selection depends on task and exposure risk.

Chemical spills: use the SDS for hazard information, contain the spill, and use appropriate absorbent; mercury spills require special cleanup.

Fire safety: PASS = Pull, Aim, Squeeze, Sweep; use a Class C extinguisher for electrical fires.

Biological spill cleanup: absorb, apply disinfectant (e.g., 1:10 bleach), allow contact time, and dispose as biohazardous waste.

Proficiency testing (PT) must be performed like patient samples; unacceptable PT results require investigation and corrective action.

CLIA complexity categories: waived, moderate complexity, and high complexity; the laboratory's certificate must match the testing performed.

A Certificate of Waiver permits only waived tests; a Certificate of Compliance or Accreditation is required for moderate- and high-complexity testing.

Moderate-complexity labs must have a laboratory director, technical consultant, and general supervisor; high-complexity labs also require a technical supervisor.

Personnel qualifications: high-complexity testing requires a director with a doctoral degree and appropriate experience; technologists need specified education and experience.

Quality assessment (QA) must include preanalytic, analytic, and postanalytic monitoring, plus review of proficiency testing and patient complaints.

Proficiency testing is required for regulated analytes; alternative assessment is allowed for unregulated analytes.

CLIA requires biennial inspection (or accreditation survey) and a current certificate; changes in ownership or location require notification.

Record retention: patient test records generally 2 years; quality control and proficiency records 2 years; some states require longer.

Anion gap = Na − (Cl + HCO3); reference ~8–12 mmol/L; elevated gap suggests MUDPILES (methanol, uremia, DKA, propylene glycol, isoniazid, lactic acidosis, ethylene glycol, salicylates).

Osmolal gap = measured osmolality − calculated (2Na + glucose/18 + BUN/2.8); gap >10 suggests unmeasured osmoles such as methanol or ethylene glycol.

Friedewald LDL = TC − HDL − (TG/5), valid only when TG <400 mg/dL; use direct LDL or non-HDL when TG exceeds this.

Corrected calcium (mg/dL) = measured Ca + 0.8 × (4.0 − albumin g/dL); ionized calcium is unaffected by albumin.

Enzymatic creatinine methods are subject to negative interference from high bilirubin and positive interference from ketoacids; Jaffe methods are less specific.

Cardiac troponin I and T rise 3–6 h after injury, peak ~12–24 h, and remain elevated for 5–14 days; CK-MB normalizes in 2–3 days.

HbA1c reflects mean glucose over ~90–120 days (RBC lifespan); NGSP-certified methods must be used, and hemoglobin variants can interfere with some assays.

Delta checks flag a result that differs from the patient's prior value by more than a set threshold; they are a key autoverification safety rule.

MCV = (Hct × 10)/RBC (fL); MCH = Hgb/RBC × 10 (pg); MCHC = Hgb/Hct × 100 (g/dL); MCHC >36 suggests spherocytosis, lipemia, or cold agglutinin artifact.

RDW-CV >14.5% indicates anisocytosis; a high RDW with low MCV favors iron deficiency over thalassemia trait.

Corrected WBC = observed WBC × (100 / (100 + nucleated RBCs per 100 WBC)); failure to correct causes falsely elevated counts in newborns.

Reticulocyte index = reticulocyte % × (patient Hct / normal Hct) ÷ maturation factor (~2 for Hct <25%); index >2 indicates adequate marrow response.

PT measures extrinsic/common pathway (factors VII, X, V, II, fibrinogen); aPTT measures intrinsic/common (VIII, IX, XI, XII, X, V, II, fibrinogen).

Mixing study: correction of a prolonged aPTT immediately after 1:1 mixing suggests factor deficiency; failure to correct suggests an inhibitor such as lupus anticoagulant or factor VIII inhibitor.

D-dimer has high sensitivity but low specificity for VTE; a negative result with low pretest probability supports exclusion of pulmonary embolism.

G6PD deficiency shows bite cells and Heinz bodies; do not transfuse or test during acute hemolysis because reticulocytes and young RBCs have higher enzyme levels.

Staphylococcus aureus: catalase positive, coagulase positive, grows in 6.5% NaCl; streptococci are catalase negative.

Lancefield grouping: group A = S. pyogenes (bacitracin susceptible), group B = S. agalactiae (hippurate positive, CAMP positive).

Enterobacteriaceae are oxidase negative, glucose fermenters, and reduce nitrate; Pseudomonas aeruginosa is oxidase positive and non-fermentative.

Blood culture bottles should be incubated at 35–37 °C and routinely held 5 days; organisms such as Brucella and HACEK require extended incubation.

CSF bacterial meningitis typical profile: elevated WBC with neutrophil predominance, high protein, low glucose (<40 mg/dL or CSF/serum ratio <0.4).

MRSA is confirmed by cefoxitin disk or oxacillin/mecA PCR; inducible clindamycin resistance is detected with the D-test.

Carbapenemase-producing organisms are screened by carbapenem MIC or disk diffusion and confirmed by PCR or phenotypic tests such as mCIM.

Urine culture colony count ≥10^5 CFU/mL of a single organism is significant in clean-catch specimens; mixed flora suggests contamination.

ABO: A has A antigen and anti-B; B has B antigen and anti-A; AB has both antigens and no antibodies; O has no antigens and both anti-A and anti-B.

Forward and reverse ABO grouping must agree; a discrepancy requires resolution before transfusion (e.g., weak subgroups, cold autoantibody, or missing reverse reaction in newborns).

Rh(D) negative patients receive D-negative RBCs; weak D testing determines whether a donor unit is labeled D positive or negative.

Antibody screen positive requires identification by panel cells; clinically significant antibodies (e.g., anti-Jka, anti-K, anti-Fya) require antigen-negative units.

Crossmatch: immediate spin detects ABO incompatibility; AHG phase detects IgG antibodies; computer crossmatch is allowed only when the antibody screen is negative and historical records agree.

RBC units stored at 1–6 °C; expiration depends on additive: AS-1/AS-3 = 42 days, CPDA-1 = 35 days, and CPD/CP2D = 21 days.

Platelets stored at 20–24 °C with continuous agitation for 5 days; never refrigerate platelets.

Transfusion reaction: stop transfusion immediately, keep IV line open with saline, and return the bag and tubing with post-transfusion samples for investigation.

Sensitivity = TP/(TP + FN); specificity = TN/(TN + FP); positive predictive value depends on disease prevalence.

ELISA: direct detects antigen, indirect detects antibody; sandwich ELISA is highly sensitive for antigen detection.

Western blot is used as a confirmatory test (e.g., HIV, Lyme); interpretation requires detection of specific bands, not just any band.

ANA by IFA: homogeneous pattern suggests anti-dsDNA or anti-histone; speckled suggests anti-Sm, anti-RNP, or anti-SSA/SSB.

Anti-dsDNA and anti-Sm are specific for SLE; anti-histone is associated with drug-induced lupus.

Rheumatoid factor is an IgM antibody against IgG Fc; anti-CCP is more specific for rheumatoid arthritis.

Complement: C3 and C4 decrease in active SLE and in immune-complex disease; CH50 measures the classical pathway.

Syphilis serology: nontreponemal tests (RPR, VDRL) are used for screening and monitoring; treponemal tests (FTA-ABS, TP-PA) confirm and remain positive for life.

Urine specific gravity by reagent strip reflects ionic concentration and is affected by pH; refractometry measures all solutes.

Reagent strip protein is most sensitive to albumin; a positive result at low pH can be a false positive from high specific gravity or alkaline urine.

Leukocyte esterase detects esterases from neutrophils; nitrite positivity indicates nitrate-reducing organisms such as Enterobacteriaceae.

Hyaline casts are normal; RBC casts indicate glomerular bleeding; WBC casts suggest pyelonephritis; waxy casts indicate chronic renal failure.

Urine pH >7.5 with positive nitrite and leukocyte esterase supports urinary tract infection; alkaline urine can also cause false-positive protein.

Synovial fluid: normal is clear, viscous, WBC <200/µL; septic fluid is turbid, low viscosity, WBC >50,000/µL with neutrophil predominance.

CSF glucose should be about 60% of serum glucose; values <40 mg/dL or a ratio <0.4 suggest bacterial or fungal meningitis.

Semen analysis reference: volume ≥1.5 mL, concentration ≥15 million/mL, total motility ≥40%, normal morphology ≥4% (WHO 2010).

PCR requires a thermostable DNA polymerase, primers, dNTPs, Mg2+, and template; each cycle doubles the target in exponential phase.

Real-time PCR quantifies product by fluorescence; Ct value is inversely proportional to starting template concentration.

Sanger sequencing is the gold standard for single-gene confirmation; next-generation sequencing provides high throughput but requires bioinformatics validation.

Karyotype resolution is ~5–10 Mb; FISH detects specific loci with ~100–200 kb resolution; microarray detects copy-number changes at kilobase resolution.

Common translocations: t(9;22) BCR-ABL in CML; t(15;17) PML-RARA in APL; t(8;21) RUNX1-RUNX1T1 in AML.

Turner syndrome is 45,X; Klinefelter is 47,XXY; Down syndrome is trisomy 21, most often from maternal nondisjunction.

Molecular testing must include positive and negative controls per run, and contamination controls such as no-template controls.

Levey-Jennings chart: results within ±2 SD are acceptable; a single result beyond ±3 SD or two consecutive beyond ±2 SD on one side is a rejection rule.

Westgard rules: 1-3s (reject), 2-2s (reject), R-4s (reject), 4-1s (reject), 10x (reject); 1-2s is a warning.

Coefficient of variation (CV) = (SD/mean) × 100; lower CV indicates better precision.

Standard precautions require gloves for all blood and body fluid contact; PPE selection depends on task and exposure risk.

Chemical spills: use the SDS for hazard information, contain the spill, and use appropriate absorbent; mercury spills require special cleanup.

Fire safety: PASS = Pull, Aim, Squeeze, Sweep; use a Class C extinguisher for electrical fires.

Biological spill cleanup: absorb, apply disinfectant (e.g., 1:10 bleach), allow contact time, and dispose as biohazardous waste.

Proficiency testing (PT) must be performed like patient samples; unacceptable PT results require investigation and corrective action.

CLIA complexity categories: waived, moderate complexity, and high complexity; the laboratory's certificate must match the testing performed.

A Certificate of Waiver permits only waived tests; a Certificate of Compliance or Accreditation is required for moderate- and high-complexity testing.

Moderate-complexity labs must have a laboratory director, technical consultant, and general supervisor; high-complexity labs also require a technical supervisor.

Personnel qualifications: high-complexity testing requires a director with a doctoral degree and appropriate experience; technologists need specified education and experience.

Quality assessment (QA) must include preanalytic, analytic, and postanalytic monitoring, plus review of proficiency testing and patient complaints.

Proficiency testing is required for regulated analytes; alternative assessment is allowed for unregulated analytes.

CLIA requires biennial inspection (or accreditation survey) and a current certificate; changes in ownership or location require notification.

Record retention: patient test records generally 2 years; quality control and proficiency records 2 years; some states require longer.