Factors for predicting positive results for anti-HAV IgM retesting among initially seronegative patients

Background and Aims: The standard diagnostic tool for acute hepatitis A is detection of anti-hepatitis A virus (HAV) immunoglobulin M (IgM). However, a negative result for anti-HAV IgM can be obtained in the early phase of infection. Among clinically suspicious seronegative patients, diagnosis of hepatitis A is sometimes recorded on retesting. Patients and Methods: This study included patients who had attended the Kyung Hee University East-West Neo Medical Center from November 2006 to October 2008. We evaluated 27 patients (15 men, 12 women) who had undergone repeated anti-HAV IgM testing. Results: Thirteen patients were diagnosed with hepatitis A after retesting, and 14 with non-hepatitis A (non-HA). High initial cutoff index (COI) for anti-HAV IgM (≥0.5), low serum total bilirubin (<1.4 mg/dl), and low platelet count (<165 × 10³/μl) were related to a positive result for anti-HAV IgM retesting, although this association was not statistically significant on multivariate analysis. In the HA group, 7 of 13 patients had an initial COI for anti-HAV IgM of >0.5 compared with none of 14 patients in the non-HA group. Conclusions: Initial COI for anti-HAV IgM, serum total bilirubin, and platelet count were helpful for predicting positive results for retesting among initially seronegative patients.