Serum alanine aminotransferase has limited predictive value for liver disease in chronic hepatitis C

Serum alanine aminotransferase (ALT) levels are sometimes used to identify patients with progressive liver disease in chronic hepatitis C. We assessed the predictive value of serum ALT at various cut-off levels, for the identification of liver disease severity.

This cross sectional study was carried out at Ziauddin University and Pakistan Medical Research Council, Karachi. Liver biopsy specimens were staged and graded according to METAVIR scoring system. Identification of overall significant liver disease (F2 or A2 and above) was the primary outcome variable. Diagnostic value of ALT was assessed through receiver operating characteristic (ROC) curve analysis.

Out of 98 patients, 42 (43%) had significant fibrosis and 26 (27%) had significant inflammatory activity. Overall significant liver disease was present in 46 (47%) patients of which 13 had widespread fibrosis. Area under the ROC curve for overall significant disease was 0.727 (95% CI 0.627-0.826). A clinically acceptable cut off level to rule out presence of clinically significant disease was found to be ≤ 20 U/L. This low level of ALT was present in 13 (13%) patients. At this cut off, sensitivity was 96%, specificity was 19%, positive predictive value was 49% and negative predictive value was found to be 85%.

Serum ALT level of ≤ 20 U/L can reliably exclude significant liver disease. Values of ALT above 20 U/L do not reliably differentiate between minimal and significant disease.