Epidemiology of primary biliary cirrhosis among women with elevated γ-glutamyl transpeptidase levels in Okinawa, Japan

We investigated the conditions among women who had an asymptomatic increase in serum γ-glutamyl transpeptidase (γ-GTP) levels, and the prevalence of primary biliary cirrhosis (PBC), in the general population. Among 4048 women who received their annual health check-up, 241 showed an elevated γ-GTP level and were invited to participate in this study. Of the 241 women, 122 participated and were examined thoroughly, including for antimitochondrial antibody (AMA) and by using liver biopsy to make a clinical diagnosis. Six (4.9%) of the 122 women were AMA positive: five were diagnosed and one was suspected of having PBC. Another two women had the criteria of PBC despite being AMA negative. PBC was detected in 5.7% (95% confidence interval (CI), 1.6–9.9%) of asymptomatic women with raised γ-GTP levels who were 6.0% of all 4048 women examined. The estimated prevalence of PBC in our area was 3400 per million women mainly over 40 years and 840 per million in the whole population. In 44% of women, the cause of chronic γ-GTP elevation was unknown; they usually showed mild and non-specific histological change differing from their liver biochemical test results.