Specimen Information

Type

Special "ARUP Serotonin Transport Tube" containing ascorbic acid (call lab for supplies)
WHOLE BLOOD

Volume

3.0 ml

Transport Info

Collect in lavender top (EDTA) tube, Place on ice
Transfer whole blood into an "ARUP Serotonin Transport Tube"
Frozen

*Specimen must be preserved and frozen within 2 hours of collection*
CRITICAL FROZEN – Separate specimens must be submitted when multiple tests are ordered

Fasting Required?

False

Clinical Significance

Aid in the diagnosis of carcinoid syndrome.

Serotonin (5-hydroxytryptamine, 5-HT) is derived from tryptophan and is carried in blood by platelets. This smooth muscle stimulant is oxidatively deaminated to 5-hydroxyindoleacetic acid (5-HIAA). Increased concentrations of circulating serotonin have been implicated in several pathologic conditions that may involve peripheral serotonergic mechanisms: carcinoid syndrome, migraine, schizophrenia, essential hypertension, Huntington disease, and Duchenne's muscular dystrophy. Slight increases may be seen in dumping syndromes, acute intestinal obstruction, cystic fibrosis, acute myocardial infarction (MI), and non-tropical sprue. In carcinoid tumors, serotonin is variably metabolized to 5-HIAA, depending upon the tissue of origin (foregut, midgut, hindgut). The majority of patients usually have very high levels of urinary 5-HIAA. Metastasizing abdominal carcinoid tumors will often produce concentrations greater than 400 ng/mL. Medications which may affect serotonin concentrations include: lithium, MAO inhibitors, methyldopa, morphine, and reserpine. In general, serotonin-containing foods do not interfere significantly.