Serotonin, Whole Blood (In-Ofc Collection Only)

Diagnose carcinoid syndrome. The classical syndrome includes flushing and vasomotor instability, diarrhea, hepatomegaly, and endocardial lesions. Ectopic production may occur from oat cell carcinomas of lung, islet cell tumors of pancreas, and medullary carcinoma of the thyroid. Carcinoid tumors occur in multiple endocrine neoplasia, types I and II.

Serotonin is produced by cells of the APUD system, including the enterochromaffin (Kulchitsky) cells distributed through the mucosa of the gastrointestinal tract. Most serotonin in blood is usually concentrated in platelets, which release it during blood coagulation. Serotonin may be measured to confirm the diagnosis of carcinoid syndrome. The carcinoid syndrome is usually caused by primary carcinoids of the ileum, but the syndrome is occasionally caused by primary carcinoids of the stomach. Other organs give rise to carcinoids including pancreas, duodenum, bronchus, and ovary. Most patients with the carcinoid syndrome have hepatic metastases.

1. Goldsmith BM, Feinstein C, Munson S, et al. Determination of a reference range for whole blood serotonin in a pediatric population using high pressure liquid chromatography with electrochemical detection. Clin Biochem. 1986; 19(6):359-363. PubMed 3581469

Monoamine oxidase inhibitor drugs should be discontinued for at least one week prior to sampling since they tend to increase the level of serotonin.