Serotonin, Serum
Use
The serotonin, serum test is used in conjunction with, or as an alternative to, first-order tests in the differential diagnosis of isolated symptoms suggestive of carcinoid syndrome, particularly flushing. It serves as a second-order test in the follow-up of patients with known or treated carcinoid tumors. Carcinoid syndrome symptoms can include flushing, diarrhea, right-sided valvular heart lesions, and bronchoconstriction. This test measures the serotonin levels in serum to aid in diagnosing potentially serotonin-secreting carcinoid tumors that may be affecting a patient's condition.
Special Instructions
Patients should avoid medications that elevate serotonin levels, such as lithium, monoamine oxidase inhibitors, methyldopa, morphine, reserpine, or selective serotonin reuptake inhibitors (SSRIs) for a minimum of 72 hours before specimen collection. A red top tube is preferred for collection, and the specimen should be centrifuged as soon as blood has clotted, with serum aliquoted into a plastic vial.
Limitations
This test is not FDA cleared or approved, and its performance has been determined consistent with CLIA requirements by the Mayo Clinic. False negatives can occur due to SSRIs or other medications. Serotonin levels are affected by various factors, including medications and diet, which can lead to diagnostic confusion. Ordinary or platelet-poor plasma specimens are unsuitable for this test. In patients with extensive serotonin-producing tumors, there may be a plateau effect due to platelet storage capacity limits, leading to no linear relationship between tumor burden and blood serotonin levels.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 27057-9
- 27057-9
Result Turnaround Time
5-8 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2.5 mL
Minimum Volume
1.1 mL
Container
Plastic vial
Collection Instructions
Centrifuge as soon as blood has clotted and aliquot serum into a plastic vial.
Patient Preparation
Patient should not take medications that may elevate serotonin levels for at least 72 hours before specimen collection.
Causes for Rejection
Ordinary or platelet-poor plasma specimens are unsuitable.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 4 days |
| Refrigerated | 21 days |
| Frozen | 90 days |