The urine of a 9-year-old boy suffering from extreme body odour was assayed for trimethylamine (TMA) by gas chromatography – mass spectrometry. A trapping column bed, specifically designed for volatile compounds, was used in the mass spectrometry. The diagnosis of rare trimethylaminuria was confirmed by the presence of appreciable urinary TMA. Urinary TMA concentrations were reduced to virtually nil after the elimination of the major choline sources (fish and eggs) from the diet.
