Lactulose in trimethylaminuria, the fish-odour syndrome

We have measured the urinary excretion of trimethylamine in two sisters with trimethylaminuria (the fish-odour syndrome). On a restricted diet the patients still excreted increased quantities of trimethylamine, and this did not alter following a fourteen-day course of lactulose. Dietary provocation produced a rise in urinary trimethylamine which was abolished by fourteen days' pretreatment with lactulose. The case histories illustrate the tendency for delay in reaching this diagnosis and the psychological damage caused by the condition.