Clinical Laboratory Techniques & Procedures Flashcards
7 cards from real CLT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Clinical Laboratory Techniques & Procedures flashcards as text
Which of the following pre-analytical errors most commonly causes falsely elevated potassium results?
Answer: Specimen hemolysis releasing intracellular potassium
Hemolysis ruptures red blood cells, releasing their high intracellular potassium content into the plasma/serum, causing spuriously elevated potassium results.
The Beer-Lambert law states that absorbance is directly proportional to:
Answer: The concentration of the absorbing substance and the path length
Beer-Lambert law: A = εlc, where A = absorbance, ε = molar absorptivity, l = path length, and c = concentration; absorbance is directly proportional to both path length and concentration.
A reagent lot change in a clinical laboratory requires which of the following steps before reporting patient results?
Answer: Parallel testing with the old lot to verify comparable performance
Parallel testing (running patient samples with both old and new reagent lots) verifies that the new lot produces clinically equivalent results before patient reporting.
Which type of microscopy is most useful for identifying Treponema pallidum in a clinical specimen?
Answer: Dark-field microscopy
T. pallidum is too thin to resolve by brightfield microscopy; dark-field illumination makes the organism appear as a bright, motile spirochete against a dark background.
For a prothrombin time (PT) test, the blood-to-citrate ratio in the collection tube must be maintained at 9:1 to avoid:
Answer: Citrate dilution effect causing artificially prolonged clotting times
If the tube is underfilled, excess citrate relative to plasma dilutes calcium needed for re-calcification in the assay, causing a falsely prolonged PT.
A technologist observes rouleaux formation on a peripheral blood smear. This finding is most commonly associated with:
Answer: Elevated plasma proteins such as fibrinogen or immunoglobulins
Rouleaux (stacked-coin RBC arrangement) is caused by elevated plasma proteins (fibrinogen, immunoglobulins) that reduce the normal negative charge repulsion between erythrocytes.
In performing a KOH (potassium hydroxide) preparation for fungal examination, the purpose of the KOH is to:
Answer: Dissolve keratin and cellular debris to reveal fungal elements
KOH digests proteinaceous material, keratin, and cellular debris, clearing the background so hyphae, pseudohyphae, or yeast cells are visible without staining.