MLPAO Clinical Chemistry Advanced Concepts Flashcards
6 cards from real MLPAO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 MLPAO Clinical Chemistry Advanced Concepts flashcards as text
What is the primary advantage of using enzymatic creatinine assays over the Jaffe method?
Answer: Greater specificity with fewer interferences
Enzymatic creatinine assays offer greater specificity than the Jaffe method because they are less susceptible to interference from non-creatinine chromogens such as glucose, acetoacetate, cephalosporins, and bilirubin. This is particularly important in neonatal and pediatric samples.
Which calculation is used to estimate glomerular filtration rate (eGFR) in Canadian clinical practice?
Answer: CKD-EPI equation
The CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) equation is recommended for estimating GFR in Canadian clinical practice. It uses serum creatinine, age, and sex and is more accurate than the older MDRD equation, particularly at higher GFR values.
What causes a delta check failure in the clinical chemistry laboratory?
Answer: A significant difference between a patient's current and previous result
A delta check compares a patient's current test result with their previous result and flags significant changes that may indicate specimen misidentification, sample mix-up, or acute clinical change. The acceptable delta varies by analyte and is typically expressed as a percentage or absolute change.
Which hormone is measured using a stimulation test with cosyntropin (synthetic ACTH)?
Answer: Cortisol
The cosyntropin stimulation test measures cortisol response to synthetic ACTH to assess adrenal gland function. A normal response shows cortisol rising above 500 nmol/L, while an inadequate response suggests primary adrenal insufficiency (Addison disease).
What is the principle of the ion-selective electrode used for measuring ionized calcium?
Answer: Potentiometry using a calcium-selective membrane
Ionized calcium is measured by potentiometry using an electrode with a calcium-selective membrane (typically containing a calcium-selective ionophore). The electrode generates a voltage proportional to the logarithm of ionized calcium activity in the specimen.
Why is it important to measure ionized calcium rather than total calcium in critically ill patients?
Answer: Ionized calcium represents the biologically active form unaffected by albumin changes
Ionized calcium is the physiologically active form and is preferred in critically ill patients because total calcium is significantly affected by albumin levels, which are frequently abnormal in these patients. Approximately 40% of total calcium is bound to albumin, so hypoalbuminemia can mask true calcium status.