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Denver Genetic Laboratories
 

Trimethylamine (TMA) and TMA N-oxide (TMAO), Quantitative, Urine

Clinical Test Information - UCD Biochemical Genetics Laboratory


 


CPT Code:

83789 x 10

Availability:

Monday - Friday, 0800 - 1700.

Turnaround Time:

Three weeks.

Minimum Volume:

1.0 mL (no more than 5 mL preferred).

Specimen Handling:

Morning void urine, collected when the patient is eating an unrestricted diet and odor is present. Please note that very dilute urine can not be accurately tested. Acidification of the urine to pH=4 is preferred, although not necessary. Freeze the urine immediately in a durable, tightly-sealed specimen tube and ship frozen on dry ice. See additional information below.

Interpretive Reference Range:

     %TMAO = TMAO/(TMAO+TMA)
     Normal %TMAO > 92%

Use:

Diagnosis of trimethylaminuria.

Methodology:

Stable isotope dilution tandem mass spectrometry (MS/MS).

Additional Information:

Although not absolutely necessary, this laboratory strongly recommends the following choline load protocol:

A pre-choline load urine specimen is collected as described above under "Specimen Handling." The pre-choline load urine specimen should be acidified to pH=4 (if possible), and frozen immediately in a durable, tightly-sealed specimen tube and stored frozen until shipment. A second urine specimen should then be collected post-choline load, about 12 hours after the patient has ingested Choline Bitartrate*
[5 gm (5000 mg) for patients >12 years and weighing more than 56 kg (120 lbs); 2.5 gm (2500 mg) for patients >12 years and weighing 56 kg or less], taken with orange juice or water. Ingestion of a choline load may cause stomach upset in some patients, and is not recommended for patients aged less than 12 years. The post-choline load urine specimen should be acidified to pH=4 (if possible), and frozen immediately in a durable, tightly-sealed specimen tube and stored frozen until shipment. Please clearly label each of the specimens “pre-choline load” or “post-choline load.” Ship the frozen specimens on dry ice.

* For patients in the United States, this laboratory recommends the use of Choline Bitartrate from Douglas Laboratories, provided in 500 mg capsules (10 capsules = 5000 mg). Although not sold directly by Douglas Laboraties, this product is readily available at an affordable price in many U.S. stores or from many internet retailers (link opens in a new window).​​​