Prognosis of adult-onset idiopathic bile acid malabsorption

Background: From 1986 to 1993, 150 patients were investigated with the Se-7 5-homocholic acid taurine (SeHCAT) test as a late step in the investigation of chronic diarrhoea. On basis of low SeHCAT values and response to choles tyramine treatment, 33 patients were initially classified as having idiopat hic bile acid malabsorption (IBAM). The aim was to describe the long-term c linical course of the disease and to assess the reliability of the SeHCAT t est in diagnosing IBAM. Methods: The methods included 1) clinical follow-up with patient interview combined with information from medical records and 2) repeated SeHCAT test. Results: The diagnosis of IBAM had to be revised i n three cases (inflammatory bowel disease in two patients, Clostridium diff icile infection in one). Six patients were lost to follow-up and a further four patients were excluded from re-examination either because of old age ( >80 years) or bowel resection, leaving 20 patients for re-examination, of w hich 16 completed both clinical follow-up and a new SeHCAT test. The median duration of symptoms before initial SeHCAT test was 2.5 (1-30) years. In 1 3 of 16 patients symptoms persisted and SeHCAT values remained low and almo st identical to the initial value after a median observation time of 88 (51 -113) months. Despite initial response to treatment with cholestyramine, si x patients had to discontinue treatment because of adverse effects or other compliance problems. In three patients the SeHCAT value showed a considera ble increase, and bowel function had correspondingly normalized in these ca ses. Conclusion: The study confirms the reliability of the SeHCAT test in d iagnosing IBAM. Despite adult onset of symptoms, only a few patients improv e after several years' observation. Treatment with cholestyramine is genera lly effective but not always tolerated.