Question:easy
HIAA (5-hydroxyindoleacetic acid) is present in the urine in which condition?
HIAA (5-hydroxyindoleacetic acid) is present in the urine in which condition?
Show Hint
5-HIAA is a serotonin metabolite - which serotonin-secreting tumour raises it?
Updated On: Jun 23, 2026
- Alkaptonuria
- Albinism
- Carcinoid
- Phenylketonuria
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Identify the parent molecule of 5-HIAA. It is the end metabolite of serotonin, so a high urinary 5-HIAA signals a serotonin-secreting process.
Step 2: The classic serotonin factory is the carcinoid tumour, a neuroendocrine growth of the gut. Its hormone output produces the triad of flushing, cramping and diarrhoea known as carcinoid syndrome.
Step 3: Confirming the tumour relies on measuring elevated 24-hour urinary 5-HIAA, exactly the link the question is testing.
Step 4: Cross off the others by their own signatures - homogentisic acid (alkaptonuria), absent melanin (albinism), phenylketones (phenylketonuria). None touches the serotonin pathway, so carcinoid is the only fit.
\[\boxed{\text{Carcinoid}}\]
Step 2: The classic serotonin factory is the carcinoid tumour, a neuroendocrine growth of the gut. Its hormone output produces the triad of flushing, cramping and diarrhoea known as carcinoid syndrome.
Step 3: Confirming the tumour relies on measuring elevated 24-hour urinary 5-HIAA, exactly the link the question is testing.
Step 4: Cross off the others by their own signatures - homogentisic acid (alkaptonuria), absent melanin (albinism), phenylketones (phenylketonuria). None touches the serotonin pathway, so carcinoid is the only fit.
\[\boxed{\text{Carcinoid}}\]
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