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HelpTest Code SERU Serotonin, 24 Hour, Urine
Reporting Name
Serotonin, 24 Hr, UPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Useful For
The diagnosis of a small subgroup of carcinoid tumors that produce predominately 5-hydroxytryptophan (5-HTP) but very little serotonin and chromogranin A
Follow-up of patients with known or treated carcinoid tumors that produce predominately 5-HTP but very little serotonin and chromogranin A
Method Name
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
Additional Testing Requirements
First-line testing for the diagnosis of carcinoid tumors with symptoms suggestive of carcinoid syndrome consists of urinary serotonin (this test), urinary 5-HIAA (HIAA / 5-Hydroxyindoleacetic Acid [5-HIAA], 24 Hour, Urine), and serum chromogranin A (CGAK / Chromogranin A, Serum).
Necessary Information
24-Hour volume (in milliliters) is required.
Specimen Required
Patient Preparation:
1.Patients should not eat avocados, bananas, butternuts, cantaloupe, dates, eggplant, grapefruit, hickory nuts, honeydew melon, kiwifruit, melon, nuts, pecans, pineapple, plantains, plums, tomatoes, or walnuts, which are high in serotonin for 48 hours before and during collection.
2. Patient should discontinue medications that may elevate urine serotonin concentration including lithium, monoamine oxidase-inhibitors, methyldopa, morphine, and reserpine. Patient should also discontinue use of selective serotonin reuptake inhibitors (SSRI; eg, PROZAC) that can lead to depletion of platelet serotonin levels and result in false-negative urine serotonin tests.
3. Patient should avoid heavy nicotine consumption during the 24-hour collection period.
Supplies: Urine Tubes, 10mL (T068)
Container/Tube: Plastic, 10-mL urine tube
Specimen Volume: 5 mL
Collection Instructions:
1. Add 25 mL of 50% acetic acid as preservative at start of collection.
2. Collect urine for a full 24 hours (required) and record the total volume.
3. Refrigerate specimen during collection.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
Specimen Type
UrineSpecimen Minimum Volume
2.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Urine | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days | ||
| Ambient | 48 hours |
Reject Due To
| Gross hemolysis | OK |
Reference Values
≤210 mcg/24 h
Reference values apply to all ages.
Interpretation
It is usually impossible to diagnose asymptomatic, small carcinoid tumors by measurement of serum or urine serotonin, urine 5 hydroxyindoleacetic acid (5-HIAA), or serum chromogranin A. By contrast, 1 or more of these markers are elevated in most patients with more advanced and symptomatic tumors, usually to levels several times the upper limit of the reference interval.
In patients with advanced and symptomatic tumors the following patterns of tumor marker elevations are observed:
-Serum or whole blood serotonin is elevated in nearly all patients with midgut tumors, but only in approximately 50% of those with foregut carcinoids, and in no more than 20% of individuals with hindgut tumors, because foregut and hindgut tumors often have low or absent 5-hydroxytryptophan (5-HTP) decarboxylase activity and, therefore, may produce little, if any, serotonin.
-Urine 5-HIAA is elevated in almost all carcinoid-syndrome patients with midgut tumors, in about 30% of individuals with foregut carcinoids, but almost never in hindgut tumors.
-Serum chromogranin A measurements are particularly suited for diagnosing hindgut tumors, being elevated in nearly all cases, even though serotonin and 5-HIAA are often normal. Chromogranin A is also elevated in 80% to 90% of patients with symptomatic foregut and midgut tumors.
-Urine serotonin is in most circumstances the least likely marker to be elevated. The exception is tumors (usually foregut tumors) that produce predominately 5-HTP, rather than serotonin, and also secrete little, if any, chromogranin A. In this case, circulating chromogranin A, circulating serotonin levels, and urine 5-HIAA levels would not be elevated. However, the kidneys can convert 5-HTP to serotonin, leading to high urine serotonin levels.
Urine serotonin measurements are not commonly employed in carcinoid tumor follow-up. The exceptions are patients with tumors that almost exclusively secrete 5-HTP, as summarized above. In these individuals, urine serotonin is the tumor marker of choice to monitor disease progression.
In all other patients, disease progression is monitored best using urinary 5-HIAA and serum chromogranin A measurements. These markers are usually proportional to the patient's tumor burden over a wide range of tumor extent and tumor secretory activity.
Day(s) Performed
Monday, Wednesday, Friday
Report Available
5 to 8 daysTest Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
84260
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| SERU | Serotonin, 24 Hr, U | 18253-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 26603 | Serotonin, 24 Hr, U | 18253-5 |
| TM80 | Collection Duration (h) | 13362-9 |
| VL67 | Volume (mL) | 3167-4 |
Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.