Diagnosis of trimethylaminuria requires the measurement of TMA and TMAO in urine, which should be collected after an evening meal containing substrate.
Trimethylamine (TMA), formed in the intestine by bacterial action on various foods, is absorbed across the gut wall and oxidised in the liver to trimethylamine oxide (TMAO) by flavin-containing monooxygenase 3 (FMO3).
Excess TMA results in a characteristic “fishy” odour in sweat, breath and urine – trimethylaminuria (TMAU). This may be primary TMAU, caused by biallelic mutations in the FMO3 gene and subsequent loss of FMO3 function, or secondary TMAU, due to dietary overload, intestinal bacterial overgrowth or urinary tract infection5.
Sufferers can meet serious social difficulties, leading to isolation and depression. Symptoms can be improved by dietary restriction of seafood, lecithin-containing fish oil supplements, liver, kidney, legumes, eggs, peanuts, meat - foods high in TMAO or choline; of brassicas which contain indols (inhibitors of FMO3 enzyme activity). Antibiotics reduce bacterial production of TMA and use of pH 5.5 soaps help make it less volatile. In the case of mutations that do not completely abolish FMO3 activity, supplements of riboflavin might help maximize residual enzyme activity. Fermented foods or drinks may help reduce bacterial production. There are support groups for patients with body odour: https://www.metabolicsupportuk.org email: email@example.com
Early morning urine
Specialist Chemistry freezer
Eat an evening meal containing 250g MARINE fish eg shark NOT TUNA. Fish and chips is good but ensure the fish component is actual fish (not batter). Alternatively 2 eggs and 400g "baked" haricot or soya beans, or 250g liver or kidney. Collect first urine next morning.
If overnight - Frozen
LCMS we measure both Trimethylamine and Trimethylamine oxide and report TMA to total amine ratio
Trimethylamine FMO3 sequencing can be performed at CHL, but will only be performed if a urine screening test is positive.
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