Clinical Testing & Analysis Flashcards
7 cards from real MLS 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 Testing & Analysis flashcards as text
A serum troponin I is elevated 6 hours post chest pain onset and again at 12 hours. This pattern is most consistent with:
Answer: Acute myocardial infarction
Serial rise and fall of cardiac troponin I within the characteristic kinetic window (peaks ~12–24 hr, elevated up to 7–10 days) is the hallmark of acute MI.
Which quality control rule indicates a systematic error when both controls shift in the same direction across consecutive runs?
Answer: 10x Westgard rule
The 10x rule flags systematic error when 10 consecutive control values fall on the same side of the mean, suggesting reagent or calibration drift.
A patient has elevated serum ammonia with normal liver enzymes. Which diagnosis should be considered first in a neonate?
Answer: Urea cycle disorder
Urea cycle disorders present in neonates with hyperammonemia and normal liver enzymes because the enzymatic defect is in the urea cycle itself, not hepatocytes.
The Coombs (antiglobulin) test is used to detect:
Answer: Antibody or complement bound to red cell surfaces
The direct antiglobulin test (DAT) uses anti-human globulin to detect IgG or complement components already coating patient RBCs in vivo.
A gram-positive coccus in clusters is catalase-positive and coagulase-positive. Identification is:
Answer: Staphylococcus aureus
S. aureus is the only clinically significant Staphylococcus that is coagulase-positive; this distinguishes it from coagulase-negative staphylococci.
An anion gap of 24 mEq/L (reference 8–16) with low bicarbonate and normal chloride best indicates:
Answer: High anion gap metabolic acidosis
An elevated anion gap with metabolic acidosis indicates accumulation of unmeasured anions such as lactate, ketones, uremic acids, or salicylate.
Which staining method is the gold standard for detecting acid-fast organisms in clinical specimens?
Answer: Ziehl-Neelsen (carbol fuchsin) stain
The Ziehl-Neelsen stain uses carbol fuchsin heated to penetrate the mycolic acid-rich cell wall of acid-fast bacilli, which resist decolorization with acid-alcohol.