Question 11.1 from the first paper of 2012 represents the one and only time the carcinoid neuroendocrine neoplastic syndrome has appeared in the CICM fellowhsip exam. In this question, the candidates were expected to make this diagnosis on the basis of historical features (facial flushing, diarrhoea, fatigue) and the right-sided murmur of tricuspid regurgitation. Only 10% of the candidates were able to do this. In order to improve the ratio, the following chapter is a brief point-form summary of the important things a non-endocrinologist needs to know about this condition.
The majority of this material is derived from the UpToDate article on this topic, as well as the MJA article by Modlin et al (2010).
Twenty-four-hour measurement of urinary 5-hydroxyindole-3-acetic acid (5-HIAA), which is the degradation product of serotonin, is apparently 88% specific for serotonin-producing carcinoid tumours.
The MJA article cautions that tryptophan/serotonin-rich foods (bananas, avocados, plums, eggplants, tomatoes, plantains, pineapples and walnuts) can produce a falsely elevated 5-HIAA level.
Serum chromogranin-A is a much better test, because it is more reliable, does not require 24 hours of urine collection, and can be later used to monitor treatment.
Oates, John A., and Albert Sjoerdsma. "A unique syndrome associated with secretion of 5-hydroxytryptophan by metastatic gastric carcinoids." The American journal of medicine 32.3 (1962): 333-342.1
Lundin, L., et al. "Carcinoid heart disease: relationship of circulating vasoactive substances to ultrasound-detectable cardiac abnormalities." Circulation 77.2 (1988): 264-269.
Modlin, Irvin M., et al. "Gastrointestinal neuroendocrine (carcinoid) tumours: current diagnosis and management." Med J Aust 193.1 (2010): 46-52.
Stridsberg, Mats, et al. "Measurements of chromogranin A, chromogranin B (secretogranin I), chromogranin C (secretogranin II) and pancreastatin in plasma and urine from patients with carcinoid tumours and endocrine pancreatic tumours." Journal of Endocrinology 144.1 (1995): 49-59.