Clinical Testing & Analysis Flashcards
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Read the first 7 Clinical Testing & Analysis flashcards as text
A random urine albumin-to-creatinine ratio (ACR) of 45 mg/g in a diabetic patient indicates:
Answer: Moderately increased albuminuria (microalbuminuria)
An ACR of 30–300 mg/g is classified as moderately increased albuminuria (formerly microalbuminuria) and is an early marker of diabetic nephropathy.
In flow cytometry, which parameter is used to measure cell size?
Answer: Forward scatter (FSC)
Forward scatter (FSC) measures light deflected in the forward direction proportional to cell volume/size, while side scatter reflects internal complexity.
A blood culture flags positive after 18 hours of incubation. Gram stain shows gram-positive diplococci. Most likely organism in an adult with meningitis is:
Answer: Streptococcus pneumoniae
S. pneumoniae appears as lancet-shaped gram-positive diplococci and is the leading cause of bacterial meningitis in adults; Neisseria is gram-negative.
A patient's RBC indices show MCV 110 fL and hypersegmented neutrophils on smear. The most likely cause is:
Answer: Vitamin B12 or folate deficiency
Megaloblastic anemia from B12 or folate deficiency produces macrocytosis (elevated MCV) and neutrophil hypersegmentation (≥5 lobes) due to impaired DNA synthesis.
The principle behind the colorimetric creatinine assay (Jaffe reaction) involves:
Answer: Creatinine reacting with picric acid in alkaline solution to form an orange-red complex
The Jaffe reaction is a non-enzymatic method in which creatinine reacts with alkaline picrate to produce an orange-red chromogen measured spectrophotometrically.
Which platelet function test measures the ability of platelets to adhere and aggregate under high shear conditions, simulating arterial flow?
Answer: PFA-100 (Platelet Function Analyzer)
The PFA-100 uses apertures coated with collagen/ADP or collagen/epinephrine to measure platelet plug formation under high-shear flow, closely mimicking primary hemostasis in small vessels.
A laboratory receives a serum sample that is severely lipemic. Which analyte is MOST likely to be spuriously decreased due to this interferent?
Answer: Sodium (by indirect ISE or flame photometry)
Severe lipemia decreases the aqueous fraction of serum, causing pseudohyponatremia when sodium is measured by indirect ISE or flame photometry; direct ISE methods are unaffected.