Patients with slightly elevated alanine aminotransferase (ALT) levels are at increased risk of hepatitis C infection and should undergo further investigation, a study from the Netherlands has concluded.

Using regional primary care lab service data, the researchers identified 750 patients referred by their GP for liver function tests who had mild elevation of ALT (30-100 IU/L).

All 750 samples were further tested anonymously for anti-HCV antibody and HCV PCR to identify hepatitis C infection, and HBsAg and anti-HBc for hepatitis B infection.

In this cohort, the prevalence of chronic hepatitis C infection was 1.6% in patients with an ALT of 50-70 IU/L and 1.2% in those whose ALT was 70-100 IU/L. Hepatitis C prevalence was normal ( ≤ 0.1%) in patients with an ALT of 30-50 IU/L.

Hepatitis B prevalence was at general population levels ( ≤ 0.4%) at all levels of ALT elevation.

Hepatitis B and C are increasingly important causes of serious liver disease in the UK, and both often remain undetected. Significant numbers of primary care patients are found to have low level elevation of ALT when liver function tests are carried out.

This study asked the questions ‘are primary care patients with mild ALT elevation at increased risk of hepatitis B or C and if so ‘what is the cut-off point for effective viral hepatitis screening’?

The authors recommend that when ALT is found to be elevated between 50 and 100 IU/L, risk factors for hepatitis C infection (primarily injecting drug use) should be sought, and testing for hepatitis C recommended, particularly when there is no other obvious explanation for the elevation.

Dr Jez Thompson

• Helsper C, van Essen G, Frijling BD,

de Wit N. Follow-up of mild alanine aminotransferase elevation identifies hidden hepatitis C in primary care.

Br J Gen Pract 2012;62:144-145