Fish odour syndrome

Fish odour syndrome (trimethylaminuria) is a metabolic syndrome caused by a bnormal excretion of trimethylamine in the breath, urine, sweat, saliva and vaginal secretions. Trimethylamine is derived from the intestinal bacteria l degradation of foods rich in choline and carnitine and is normally oxidis ed by the liver to odourless trimethylamine N-oxide which is then excreted in the urine. Impaired oxidation of trimethylamine is thought to be the cau se of the fish odour syndrome and is responsible for the smell of rotting f ish. Certain foods rich in choline exacerbate the condition and the patient s have a variety of psychological problems. Recognition of the condition is important as dietary adjustments reduce the excretion of trimethylamine an d may reduce the odour. Occasionally, a short course of metronidazole. neom ycin and lactulose ma suppress production of trimethylamine by reducing the activity of gut microflora.