Trimethylaminuria

Abnormal urinary excretion of trimethylamine (TMA) signals the presence of trimethylaminuria, an inborn error of metabolism presenting with body odor of putrid fish. This article summarizes the nine reported cases (including three studied in our laboratory) and describes a rapid quantitative assay. Values of TMA are presented for 95 controls (72 children), three cases of TMA uria, and two mothers. Intestinal bacteria metabolize ingested choline to TMA which is normally converted in tissues to the non-odorous TMA-oxide. This latter step is apparently defective in cases of TMA uria. Oral choline loading greatly enhances urinary TMA, confirming questionable cases. Data on excretion of TMA post-choline load are presented for cases and mother as well as for one case during choline restriction in order to remove the odor totally. The severe psycho/social problems related to this odor and the therapeutic response to choline restriction make this a diagnosis that should not be missed--a goal requiring wider capability in the laboratory and greater awareness on the part of the physician.