This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Phenylalanine and Tyrosine metabolism Detail, Subject name: Biochemistry
Positive Ferric chloride urine test is due to: 
Select and explain. 
A. Phenylalanine, B. Phenylacetate, C. Phenylpyruvate, D. Phenylaspaate
C: Phenylpyruvate
Answer: C: Phenylpyruvate 
Explanation: Diagnostic test for phenylketonuria: This is a screening test in urine sample for phenyl ketones and hence gives positive result for phenyl pyruvate Positive for:- Phenylketonuria Tyrosinemia MSUD Alkaptonuria