Question

Vanillylmandelic acid (VMA) is excreted in urine in which condition?

• A. Alkaptonuria
• B. Phenylketonuria
• C. Pheochromocytoma
• D. Diabetic ketoacidosis

Hint:

VMA is a catecholamine metabolite, so think of a catecholamine-secreting tumour.

Answer 1

The Correct Option is C

Step 1: VMA is the major end product of catecholamine (epinephrine and norepinephrine) breakdown and is excreted in urine.

Step 2: In pheochromocytoma (and neuroblastoma), tumour cells overproduce catecholamines, so their metabolism generates large amounts of VMA, raising urinary VMA. So the answer is pheochromocytoma.

Step 3: Urinary VMA is therefore a useful screening test for pheochromocytoma and for following neuroblastoma and ganglioneuroma.

Step 4: The distractors raise different metabolites: alkaptonuria raises homogentisic acid, phenylketonuria raises phenylpyruvate and phenyllactate, and diabetic ketoacidosis raises ketone bodies, none of which is VMA.