Serum total bile acid levels in patients receiving rifampicin and isoniazid.

Serum bile acid levels in 61 patients receiving daily doses of rifampicin and isoniazid for the treatment of tuberculosis have been investigated. Bile acids were measured using 3 alpha-hydroxysteroid dehydrogenase in a continuous-flow system. Abnormally elevated levels were found in 44 patients (72%) during the period of study up to 80 days after onset of treatment. The results showed a mean of 24.9 mumol/l and a positively skewed distribution. Whilst marginally raised levels of bilirubin were seen in some samples (mean 8.2 mumol/l), these did not reflect the marked changes observed in bile acids. Patients receiving rifampicin and isoniazid may therefore have markedly elevated levels of total serum bile acids, while other tests used to assess liver function can remain normal.