Lab Test


Fish Odor Syndrome, Trimethylaminuria Test, Volatile Amines

Test Codes

Order as a Miscellaneous Send Out.


Send Outs


Trimethylamine is a highly volatile compound and will be lost from the specimen during shipment if instructions are not followed. Contact the Send Outs Laboratory at 248-551-9045 with any questions.

Specimen Collection Criteria

Collect: 20 mL random urine in a sterile collection container. (Minimum: 1.0 mL)

Transport specimen to the Laboratory immediately after collection for processing. 

Physician Office/Draw Specimen Preparation

Specimen must be frozen (-20°C/-4°F or below) immediately after collection and maintained frozen prior to transport.

Preparation for Courier Transport

Transport: 20 mL urine, frozen (-20°C/-4°F or below). (Minimum: 1.0 mL)

Rejection Criteria

Specimens not collected and processed as indicated.

In-Lab Processing

Adjust the pH of the urine to pH 4 by adding concentrated HCl to the specimen. Seal tightly and freeze (-20°C/-4°F or below) the specimen. Do not fill containers more than 1/2 full.

Transport: 20 mL urine, frozen (-20°C/-4°F or below). (Minimum: 1.0 mL)


Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): Unacceptable
Refrigerated (2-8°C or 36-46°F): 4 hours
Frozen (-20°C/-4°F or below): Indefinite

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.


Sent to Children's Hospital Colorado, Denver, CO.


Results available within 21 days.

Reference Range

By report.

Test Methodology

Stable Isotope Dilution-Tandem Mass Spectrometry.

Clinical Utility

This assay aids in the diagnosis of trimethylaminuria. Trimethylaminuria is presumably a genetic defect in the enzymatic conversion of trimethylamine (odor of stale fish) to trimethylamine-N-oxide (non-odiferous). It causes body odor severe enough to create serious psychosocial problems. Diagnosis is made by detection of excess trimethylamine in urine. Available therapies include dietary restriction of choline (precursor of TMA) and also dietary restriction of foods containing inhibitors of TMA.

CPT Codes

83789, 82570.


Last Updated


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