Question

what is the functional test for b12 deficiency?
hypersegmented neutrophil test
methylmalonic acid test
schilling test

Explanation:

Methylmalonic acid (MMA) levels are elevated in B12 deficiency as B12 is required for the conversion of methylmalonyl - CoA to succinyl - CoA. The Methylmalonic Acid Test is a functional test for B12 deficiency as it measures a key metabolite affected by B12 status. The hypersegmented neutrophil test is a morphological blood - cell related test and the Schilling test is more about assessing B12 absorption rather than a direct functional measure of B12 deficiency in terms of metabolism.

Answer:

B. Methylmalonic Acid Test