Background: Hepatitis C (HCV) and hepatitis B (HBV) virus infection can lead to serious complications if left untreated, but often remain undetected in primary care. Mild alanine aminotransferase (ALT) elevations (30-100 IU/l) are commonly found and could be associated with viral hepatitis; unfortunately, these findings frequently remain without follow-up.
Aim: To determine if and how mild ALT elevation can be used to identify hidden HCV and HBV infection in primary care.
Design and setting: Primary care patients referred for liver enzyme testing were selected by a large primary care Diagnostic Centre (Saltro).
Method: First, 750 anonymous samples were collected in three categories of ALT elevation (30-50 IU/l, 50-70 IU/l, and 70-100 IU/l) and tested for HCV and HBV. Second, the national prevalence of each ALT elevation was estimated by analysing all annual ALT tests performed at Saltro.
Results: HCV prevalence was 1.6% and 1.2% in patients with an ALT of 50-70 IU/l and 70-100 IU/l respectively. In patients with an ALT of 30-50 IU/l, HCV prevalence was normal (≤0.1%). HBV prevalence was normal (≤0.4%) in all groups. The estimated number of ALT tests performed nationally each year in primary care was 1.1 million. An ALT of 30-50 IU/l was found in 21.1%, an ALT of 50-70 IU/l in 5.6%, and 2.6% had an ALT of 70-100 IU/l.
Conclusion: In primary care patients with an ALT level of 50-100 IU/l, HCV prevalence is tenfold the population prevalence, whereas HBV prevalence is not elevated. Therefore, diagnostic follow-up for HCV is indicated in these patients, even when other explanations for ALT elevation are present.