Serotonin, Whole Blood
Also known as: 5-HT, Whole Blood, 5-Hydroxytryptamine, Blood
Use
Serotonin measurement is used in conjunction with urinary 5-hydroxyindoleacetic acid (5-HIAA) and/or serum chromogranin A in the diagnosis of carcinoid syndrome.
Special Instructions
Sample collection practices that prevent blood clotting and oxidation of serotonin are essential. Monoamine oxidase inhibitor drugs should be discontinued for at least one week prior to sampling. Provide separate frozen specimens for each test requested to avoid delays in turnaround time.
Limitations
Most gastroenteropancreatic neuroendocrine carcinoid tumors do not produce elevated whole blood or serum serotonin levels. Other tests like 5-HIAA and chromogranin A are superior for carcinoid syndrome assessment. Medications like lithium, monoamine oxidase inhibitors, and methyldopa can elevate serotonin concentration, while selective serotonin reuptake inhibitors can reduce serotonin levels. Foods rich in tryptophan do not affect serotonin measurements. This test is primarily for cases where serotonin levels in the blood might provide additional insights beyond primary tests.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 2939-7
- 2939-7
Result Turnaround Time
3-6 days
Related Documents
For more information, please review the documents below
Specimen
Whole Blood
Volume
10 mL
Minimum Volume
Not provided
Container
Lavender-top (EDTA) tube and transport tube (LabCorp N° 33314) containing 75 mg ascorbic acid
Collection Instructions
Collect three tubes (4 mL each) of whole blood. Invert tubes at least ten times. Transfer 10 mL whole blood to transport tube with 75 mg ascorbic acid, mix thoroughly, freeze, and send entire collection to the laboratory.
Patient Preparation
Monoamine oxidase inhibitors should be stopped at least one week prior to sampling.
Storage Instructions
Freeze. Stability reflects properly prepared whole blood with ascorbic acid preservative.
Causes for Rejection
Receipt of non-frozen specimen; specimen stored without preservative
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 hours |
| Refrigerated | 24 hours |
| Frozen | 16 days |