Serotonin is an indole amine synthesized by the cells of the intestinal mucosa. It is stored in and transported by platelets but also found in many body tissues, including the CNS. Serotonin acts as a vasoconstrictor and neurotransmitter; stimulant of smooth muscle contraction, prolactin release, and GH release; and functions in hemocoagulation. Other names: 5-hydroxytryptamine.
Normal range: 50 " “200 ng/mL.
Use
Confirming the diagnosis of carcinoid tumors.
Adjunct test for 5-HIAA and chromogranin-A test to follow-up patients with carcinoid tumors.
Interpretation
Increased In
Metastasizing abdominal carcinoid tumors
Dumpling syndrome
Acute intestinal obstruction
Cystic fibrosis
AMI and nontropical sprue
Oat cell carcinoma of the lung
Pancreatic islet tumor
Thyroid medullary carcinoma
Decreased In
Down syndrome
Severe depression
Parkinson disease
Phenylketonuria (treated and untreated)
Renal insufficiency
Teratomas
Limitations
Blood serotonin is very unstable.
Medications that may affect serotonin concentrations include lithium, MAO inhibitors, methyldopa, morphine, and reserpine.
In general, foods that contain serotonin do not interfere significantly.
Slight increases may be seen in acute intestinal obstruction, acute MI, cystic fibrosis, dumping syndromes, and nontropical sprue.