Introduction Hepatitis B virus (HBV) infection is an exceptional threat for patients on haemodialysis and its presentation and clinical course in this group of patients is different from the general population. 1 The patients on haemodialysis are at increased risk of acquiring HBV infection as compared to the general population. 2 This is due to increased exposure to blood products, shared haemodialysis equipment, dialyser re- use, repeated needle insertions, breaching of skin and immunodeficiency. The prevalence and incidence of HBV infection among patients undergoing long-term haemodialysis is highly variable across different geographical regions, depending on local endemicity and enforcement of infection control measures in dialysis units. This ranges from 0.9% in US 3 to 16.8% in Taiwan 4 among dialysis patients. A countrywide survey 5 conducted by Pakistan Medical Research Council estimated that 2.5% population is infected with hepatitis B virus. Pakistan is in the low HBV prevalence area. Little work has been done in Pakistan regarding HBV infection among dialysis dependent patients. A study from Islamabad 6 revealed that 12.4% patients undergoing haemodialysis were hepatitis B surface antigen (HBsAg) positive and dialysis for more than 2 years was a significant risk factor. Patients on maintainence haemodialysis and chronic HBsAg carriage rarely develop symptoms of hepatitis, are anicteric and have mild elevations of hepatic transaminase levels but silent hepatocellular injury continues. 7 As the transaminase levels are usually depressed in patients undergoing maintainence haemodialysis, 'normal' values of these enzymes may be indicative of a pathological state. Lopes and colleagues 8 have recommended that the upper limit of normal (ULN) for alanine aminotransferase (ALT) be reduced. Patients with chronic hepatitis B infection are at an increased risk of developing liver cirrhosis, hepatic decompensation, and hepatocellular carcinoma 9 Although many patients with end-stage renal disease (ESRD) do not live long enough to develop HBV-related complications, increased risk of hepatocellular carcinoma and mortality associated with HBV is reported in the ESRD population 10 but it is controversial. There is only one study in literature which evaluated histopathological features in HBsAg Vol. 61, No. 12, December 2011 1210 Hepatitis B virus among maintainence haemodialysis patients: A report from Karachi, Pakistan Muhammad Khalid Idrees, 1 Salma Batool, 2 Ejaz Ahmed 3 Department of Nephrology, 1,3 Department of Molecular Biology & Immunology, 2 Sindh Institute of Urology and Transplantation, Karachi, Pakistan. Abstract Objective: To study the characterstics, pattern of viral markers, hepatic transaminases and other associated hepatitis virus infections among maintainence haemodialysis patients. Method: This prospective cross-sectional study was conducted at the dialysis unit of Sindh Institute of Urology and Transplantation Karachi on end-stage renal disease (ESRD) patients undergoing maintainence haemodialysis from November 2009 to April 2010. Patients on anti-viral drugs were excluded. Blood samples were taken, immediately before start of dialysis, for Hepatitis B virus serology, anti-HCV, polymerase chain reaction (PCR) for HBV DNA and biochemical tests. Abdominal ultrasound was performed for liver, spleen, portal vein diameter and presence or absence of ascites. Data analysis was done by using SPSS 10.0. The level of significance was taken as 0.05. Results: Out of 1220 ESRD patients on maintainence haemodialysis at SIUT, 124 were HBsAg positive but 26 patients were excluded as they had received anti-viral therapy. Finally 98 patients including 71 (72%) males and 27 (28%) females completed the study. The mean age was 34.98±12.67 years. Most of the patients did not have hepatitis symptoms. ALT level was raised above cutoff value of 20 IU/ml in 62.2% patients while AST was raised in 75.4% patients. HBeAg was positive in 34.6%, anti-HBe antibody was positive in 65% patients and HBV DNA was detected in 65.3%. More than half of the patients had HCV co-infection. Six patients had cirrhosis. Thirty four patients were non-replicating carriers. The mean duration of dialysis and duration of HBsAg positivity were significantly longer in those patients who had hepatitis B and hepatitis C coinfection (p<0.05). Conclusion: Hepatitis B virus infection in dialysis dependent patients is mostly asymptomatic. Mild transaminase elevation is frequently encountered. Keywords: Hepatitis B, Haemodialysis, Serology, Polymerase chain reaction, Karachi (JPMA 61: 1210; 2011). Original Article