Serotonin, Blood
Additional Codes
LAB121
Performing Laboratory

Specimen Type
Whole Blood EDTAAdditional Testing Requirements
First-line testing for the diagnosis of carcinoid tumors with symptoms suggestive of carcinoid syndrome consists of urinary 5-HIAA (HIAA / 5-Hydroxyindoleacetic Acid, 24 Hour, Urine), and serum chromogranin A (CGAK / Chromogranin A, Serum). Serotonin in whole blood (SERWB / Serotonin, Blood), serum (SER / Serotonin, Serum), and urine (SERU / Serotonin, 24 Hour, Urine) are useful in conjunction with these first-line tests.
Specimen Required
Patient Preparation: Patient should not take medications that may elevate serotonin levels, including lithium, monoamine oxidase inhibitors, methyldopa, morphine, and reserpine, or selective serotonin reuptake inhibitors (SSRI, eg, PROZAC) which can lead to depletion of platelet serotonin levels and result in false-negative serotonin results for a minimum of 72 hours before specimen collection. Some drugs with longer half-lives (i.e. fluoxetine) can require months after discontinuation for serotonin levels to return to baseline.
Supplies: Serotonin Tube (T259)
Collection Container/Tube: Lavender top (EDTA)
Submission Container/Tube: Serotonin tube containing ascorbic acid
Specimen Volume: 2.5 mL
Collection Instructions:
1. Immediately after collection, transfer approximately 2.5 mL of whole blood to the serotonin tube and mix well (any volume of whole blood from 1.5-3 mL is acceptable).
2. Immediately freeze specimen (necessary to lyse the red blood cells).
Specimen Minimum Volume
1.5 mL
Specimen Stability Information
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Whole Blood EDTA | Frozen | 90 days | SEROTONIN TUBE |
Reference Values
≤330 ng/mL
For International System of Units (SI) conversion for Reference Values, see www.mayocliniclabs.com/order-tests/si-unit-conversion.html.
Day(s) Performed
Monday, Wednesday, Friday
CPT Code Information
84260
LOINC Code Information
Test ID | Test Order Name | Order LOINC Value |
---|---|---|
SERWB | Serotonin, B | 2939-7 |
Result ID | Test Result Name | Result LOINC Value |
---|---|---|
84373 | Serotonin, B | 2939-7 |
Report Available
5 to 8 daysSpecimen Retention Time
2 weeksForms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.