Serotonin
Code:12016|CPT:84260|LOINC:27057-9
| Includes | Serotonin, Serum |
|---|
Analysis details
Methodology
- Liquid chromatography–tandem mass spectrometry (LC-MS/MS)
- High-performance liquid chromatography (HPLC)
Expected Turnaround Time
1–2 days
Special Instructions
- Record the patient’s sex on the test request form.
- Infants younger than 1 year: fast for 30–40 minutes before collection; water is allowed.
- Children 1–5 years: fast for 2–3 hours before collection; water is allowed.
- Avoid avocado, bananas, eggplant, pineapple, plums, tomatoes, and walnuts for 72 hours prior to collection.
- Fast for 12 hours before collection; consume only plain, noncarbonated water.
- If clinically appropriate and approved by the physician, stop sympathomimetic agents 14 days before collection.
- If clinically appropriate and approved by the physician, avoid all medications for 24 hours before collection.
- Avoid physical exertion and emotional stress for 24 hours before collection.
- Do not smoke during the 2 hours preceding collection.
How to use
Serotonin, Serum (5-HT; 5-hydroxytryptamine) is used in the evaluation of suspected carcinoid syndrome arising from gastroenteropancreatic neuroendocrine tumors. The result is commonly integrated with urinary 5-hydroxyindoleacetic acid (5-HIAA) and/or serum chromogranin A to improve diagnostic assessment. This test may also be used to follow patients after surgical resection of serotonin-producing tumors to help track for biochemical recurrence or persistence.
Limitations
Serotonin is synthesized from tryptophan and is stored predominantly in gastrointestinal enterochromaffin cells, which represent the major body reservoir. Additional stores are present in platelets, mast cells, the central nervous system, and other endocrine tissues. Physiologic actions include modulation of pain perception and pituitary function, regulation of vascular tone and coagulation, and control of gastrointestinal motility and secretion. Midgut neuroendocrine (carcinoid) tumors frequently produce serotonin and may also coexpress substance P. When hepatic metabolism is overwhelmed, the clinical constellation of carcinoid syndrome can emerge, characterized by flushing, secretory diarrhea, bronchospasm, and right-sided valvular heart disease. Not all gastroenteropancreatic neuroendocrine tumors increase circulating serotonin; in many cases, urinary 5-hydroxyindoleacetic acid (5-HIAA) and serum chromogranin A offer greater analytical sensitivity. In rare tumors with aromatic amino acid decarboxylase deficiency, conversion of 5-hydroxytryptophan to serotonin is limited, which further reduces serum serotonin elevations.
| Unit | ng/mL | ||||
|---|---|---|---|---|---|
| Reference interval |
| ||||
| Indications | Workup for suspected carcinoid syndrome due to gastroenteropancreatic neuroendocrine tumors, particularly when flushing, secretory diarrhea, bronchospasm, or right-sided valvular heart disease is reported, Assessment in the setting of possible intestinal obstruction, Unexplained, unintentional weight loss, Postoperative follow-up after removal of carcinoid (serotonin-secreting) tumors, Evaluation of symptoms consistent with dumping syndrome, Assessment in patients with irritable bowel syndrome–like complaints, Evaluation of suspected malabsorption syndrome, Testing in individuals with hereditary predisposition to multiple endocrine neoplasia syndromes, Evaluation of pellagra-like manifestations attributable to niacin deficiency from tryptophan shunting in carcinoid disease |
Possible Causes of Abnormal Results
Increased levels
- lithium
- methyldopa
- monoamine oxidase inhibitors
- morphine
- reserpine
Decreased levels
- selective serotonin reuptake inhibitors
Specimen Requirements
| Specimen | Serum |
|---|---|
| Container | Gold/Tiger Top (SST, Gel Separator) |
| Volume | 1 mL (min 0.5 mL) |
| Storage Instructions | Room temperature, Refrigerated, Frozen |
References
Kocha W, Maroun J, Kennecke H, et al. Consensus recommendations for the diagnosis and management of well-differentiated gastroentererohepatic neuroendocrine tumours: a revised statement from a Canadian National Expert Group. Curr Oncol. 2010;17(3):49-64. PMID: 20567626.
Meijer W, Kema I, Volmer M, Willemse PH, de Vries EG. Discriminating capacity of indole markers in the diagnosis of carcinoid tumors. Clin Chem. 2000;46(10):1588-1596. PMID: 11017936.