Chemical screening tests for cystine can produce false-positive results in the presence of urinary ketones because:
A) Cystine is not reduced by sodium cyanide
B) Cystine should be tested using only chromatography
C) The test reagent is nitroprusside
D) Cystinuria causes diabetic ketosis

Question

Quizplus · Accepted Answer

The test reagent used for screening cystine in urine is nitroprusside, which can also react with ketones present in the urine, leading to false-positive results. This is because nitroprusside reacts with both cystine and ketones, making it difficult to distinguish between them without further specific testing.

Chemical Screening Tests for Cystine Can Produce False-Positive Results in the Presence