False-positive hepatitis B test results after intravenous immunoglobulin therapy.

A 75-year-old male patient returned to our centre for peritoneal dialysis after transplantectomy due to renal transplant rejection. Routine viral screening prior to resuming dialysis indicated anti-Hepatitis B (anti-HB titre of 363 IU/L [anti-Hepatitis Bcore (anti-HBc) and Hepatitis Be antigen (HBeAg) both negative], which suggested that the patient received hepatitis B vaccination. However, both patient and the referring centre denied vaccination. The patient’s anti-HB titres decreased over time (Table 1).

Table 1.

Course of anti-HB titres and relevant events

Date	Event	Anti-HB titres (IU/L)
June 2017	Dialysis	<3, 10
October 2018	IVIG therapy
October 2018	Transplantectomy
5 November 2018	Blood test	363
29 November 2018	Blood test	195
13 December 2018	Blood test	101

During anti-rejection therapy, the patient received intravenous immunoglobulin (IVIG) therapy. The possibility of passive transfer of hepatitis B antibodies after IVIG administration resulting in false-positive hepatitis B serology and partial passive immunization following IVIG has been described [1-4].

Attention to the possibility of this passive immunization is important, as it can lead to misinterpretation of test results with implications for further treatment. This phenomenon may be more prevalent with the increased use of IVIG in transplant rejection nowadays.

CONFLICT OF INTEREST STATEMENT

None declared.