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Trimethylamine
24 Hour Urine (acid Preservative)(Phone (82)4712 to order)
Other acceptable tube types
Random urine (Plain)
Special instructions
Collect sample at the time of odour. Suggest dietary ‘choline load’ before collection i.e. high choline meal (e.g. 2 eggs + 400g baked beans/ other beans – can reduce amount in children) at 13:00 and 19:00 and collect first urine passed on day after load and until end of day (before bed).
Or collect single 20mL sample first thing on morning after choline load (e.g. in young children).
Samples containing nitrites are not suitable for analysis.
Sent away
to Sheffield Children's NHS Foundation Trust.
Reference range
Free TMA/creatinine ratio: <7.7, TMA-N-Oxide/creatinine ratio: <119, % N-Oxidation: >94%
Units
µmol/mmol creatinine
Turnaround Time
42
days
Department: Biochemistry
Clinical Application
For the diagnosis of trimethylaminuria (A.K.A. fish odour syndrome), which is a genetic disorder (autosomal recessive), arising due to an inability to metabolize trimethylamine due to a deficiency of Flavin-containing monooxygenase 3 (FMO3). Foods containing choline, carnitine and/or trimethylamine N-oxide can only be processed to trimethylamine, producing a strong, fishy odour. A secondary cause of trimethylaminuria arises due to large doses of amino-acid derivative L-carnitine (levocarnitine), or choline. Trimethylamine accumulates and is excreted in the urine, sweat and breath.
Webpage created: September 2024.
