Two cases of HBsAg seroconversion, following treatment with Tenofovir disoproxil fumarate, a nucleotide reverse transcriptase inhibitor, were reported amongst the patients with chronic hepatitis B infection attending gastrointestinal clinic in a tertiary hospital. The patients had liver biopsy done during their evaluation, following which they were commenced on the medication. Tenofovir was taken for four years and two years respectively before they lost the hepatitis B surface antigen and developed quantifiable antibodies to the surface antigen (Anti-HBs).

Loss of HBsAg is a rare event, and seroconversion in patients with CHB is even less common. Studies have shown that HBsAg loss and seroconversion is less likely with patients on the oral antiviral agents compared with pegylated interferon. Although, both patients had very low pretreatment hepatitis B viral load which might indicate strong immune response to the virus, a factor that could have been partly responsible for the seroconversion. They however, had significant liver fibrosis on histology prior to their seroconversion and will require hepatocellular cancer surveillance until normalization of the liver histology can be ascertained