RESUMEN
BACKGROUND: Trimethylaminuria is caused by a functional enzyme defect and is usually congenital. This metabolic disease is characterised by body odour resembling fish. CASE DESCRIPTION: A 7-year-old boy was referred with abnormal body odour, which his mother described as resembling fish. This odour caused mainly social problems. Because of the characteristic odour trimethylaminuria was considered. Further metabolic investigations showed a high concentration of trimethylamine in the urine, consistent with this diagnosis. CONCLUSION: Trimethylaminuria is rare, but due to its psychological and social impact it is important that it is recognised. Although bad body odour is seldom a manifestation of a metabolic disease, it should always be included in the differential diagnosis.
