Serum 7 alpha-hydroxy-4-cholesten-3-one concentrations in the evaluation of bile acid malabsorption in patients with diarrhoea: correlation to SeHCAT test.

The synthesis of bile acids is regulated by a homeostatic mechanism in which bile acids returning to the liver from the intestine inhibit their own synthesis. Serum concentrations of the bile acid intermediate 7 alpha-hydroxy-4-cholesten-3-one reflect the rate of bile acid synthesis whereas bile acid malabsorption can be determined by the SeHCAT test. This study was done to evaluate the correlation between the two tests in humans. Twenty eight patients with chronic diarrhoea were included in the study. Fasting serum was collected for the determination of 7 alpha-hydroxy-4-cholesten-3-one, and on the same day the gamma emitting bile acid analogue SeHCAT was given orally and its fractional catabolic rate assessed by repeated external counting over the upper abdomen during the next seven days. There was a highly significant positive correlation between the two tests (Rs = 0.80, p < 0.001). The results show a close relation between intestinal loss and hepatic synthesis of bile acids and imply that analysis of 7 alpha-hydroxy-4-cholesten-3-one in serum should now be evaluated as a possible convenient method for assessing bile acid malabsorption in patients with diarrhoea.