Preferred Sample Type
Suitable Specimen Types
- Plain Spot Urine
- 24 Hour Urine (Acid Collection)
Specimen Transport
First Class Post. Contact referral laboratory before sending.Sample Processing in Laboratory
UsualSample Preparation
Urine must be acidified to pH 2 with 6M HCl on receipt in laboratoryTurnaround Time
Not statedSample Stability
Urine must be acidified to pH 2 or lower with 6M HCl on receipt in laboratory.Trimethylamine (Quantitative)
General Information
Trimethylaminuria (TMAU), also known as fish odor syndrome or fish malodor syndrome, is a rare metabolic disorder that causes a defect in the normal production of the enzyme Flavin containing monooxygenase 3 (FMO3). When FMO3 activity is decreased, the body loses the ability to properly break down trimethylamine (TMA) from precursor compounds in food digestion into trimethylamine oxide (TMAO) through a process called N-oxygenation. Trimethylamine then builds up and is released in the person's sweat, urine, and breath, giving off a strong fishy odor or strong body odor.
Patient Preparation
Urine should be collected during time of odour.
A high choline diet (e.g. eggs, baked beans) is recommended for a couple of meals before collection of urine
Notes
24 hour urine collection into acid preferred. Random and/or plain urine specimens are acceptable.
Adjust pH of urine to <pH2 on receipt in laboratory (even if acid collection). If plain urine is sent to referral laboratory in error, they will acidify on receipt and still analyse.
Specimens only need to be frozen if there is to be a delay in sending to referral laboratory. Send by first class post (even if specimen has been frozen).
UTIs can interfere with the results, therefore a MSU sample for microbiology analysis must be sent at same time as sample for trimethylamine analysis.
If required also send an EDTA sample for genetic testing for mutation analysis for TMAU1/FM03
Reference Range
Provided by referral laboratory
Please note from 13 Feb 2017 new reference ranges and tests reported for TMA profile. TMA/TMA-n-oxide result has been replaced by % N-oxidation. Dimethylamine is no longer routinely analysed as part of the TMA profile - if it is required it should be requested separately.
PLEASE NOTE FROM JANUARY 2018 TOTAL TMA/CREATININE RATIO WILL NO LONGER BE REPORTED. The parameter is not directly required for diagnosis and is an assessment of the amount of dietary choline going through the pathway, which aids in the interpretation of results. The parameter will still be measured but not reported, rather a comment will be added if the value is low indicating insufficient stressing of the pathway which could lead to a false negative.