Case of Suspected Occult Hepatitis B Virus Infection Mistaken for a Transfusion-Transmitted Infection in a Hemodialysis Patient

A 73-year-old male patient undergoing hemodialysis showed an abnormal liver function test after the transfusion of two units of red blood cell (RBC). The results of the pre-transfusion test were negative HBsAg and positive anti-HBs. On the other hand, the results of the post-transfusion test were positive HBsAg and negative anti-HBs. The other test results were positive HBeAg, positive HBV DNA, and positive anti-HBc IgG. It was reported as a blood transfusion reaction in doubt of a transfusion-transmitted hepatitis B virus (HBV) infection. An examination of the blood information management system data, health insurance data, medical records, and test of storage samples showed that it was not a blood transfusion reaction. It was believed to be an occult HBV infection in an immunosuppressive patient receiving hemodialysis. Hemodialysis patients have a high prevalence of hepatitis B and C, and are classified as a risk group of occult infections. This raises the need for HBV vaccination in dialysis patients. Virus infections can be activated in dialysis patients due to the patient's immune system and other causes. If a blood transfusion is performed during this period, attention is needed because it can be mistaken for viral transmission from blood products. (Korean J Blood Transfus 2021;32:49-54)