Question

A 63-year-old man presents to your clinic complaining of episodic diarrhea and wheezing. His wife also mentions that his skin will occasionally look flushed. You suspect carcinoid syndrome. What diagnostic study is most appropriate to confirm this condition?

1) Abdominal computed tomography scan
2) Abdominal magnetic resonance imaging
3) Erythrocyte sedimentation rate
4) Twenty four-hour urine excretion of 5-hydroxyindoleacetic acid

Answer 1

To diagnose carcinoid syndrome, the most appropriate test is the 24-hour urine excretion of 5-HIAA, which checks for elevated levels indicative of the condition. While CT scans are helpful for tumor location, they do not confirm the syndrome itself.

Step-by-step explanation:

The most appropriate diagnostic study to confirm suspicions of carcinoid syndrome in a 63-year-old man presenting with episodic diarrhea, wheezing, and skin flushing is 24-hour urine excretion of 5-hydroxyindoleacetic acid (5-HIAA). This test measures the level of 5-HIAA, a byproduct of serotonin metabolism, which is often elevated in patients with carcinoid syndrome.

While imaging studies such as an abdominal computed tomography (CT) scan can be useful for locating the primary tumor and any metastasis, they do not confirm the diagnosis of carcinoid syndrome. Blood tests like erythrocyte sedimentation rate (ESR) are non-specific and an abdominal magnetic resonance imaging (MRI) would offer detailed imaging but is not the initial test of choice for this diagnosis. After a 5-HIAA result indicating carcinoid syndrome, further imaging may be warranted to localize the tumor.