Whole Blood Serotonin Test - Serotonin, Whole Blood Test

A whole blood serotonin test is a quantitative measurement of the concentration of the neurotransmitter and hormone serotonin (5-hydroxytryptamine - 5-HT) in whole blood. Approximately 95% of the body's serotonin is stored in platelets (found in whole blood), while the remainder is free in plasma. A significantly elevated serotonin level is an important indicator of a carcinoid tumor, a rare type of neuroendocrine tumor that secretes serotonin and other amines.