Objective: Immune thrombocytopenic purpura could occur as an extrahepatic manifestation of hepatitis C virus infection. The aim of this study was to clinically analyze hepatitis C virus-positive cases with immune thrombocytopenic purpura and to examine the relationship between hepatitis C virus and immune thrombocytopenic purpura.

Methods: Eight hepatitis C virus-positive patients with immune thrombocytopenic purpura were compared with 67 cases with chronic hepatitis C without immune thrombocytopenic purpura. We examined various clinical and hematological parameters including platelet and platelet-associated immunoglobulin G.

Results: Two men and 6 women with hepatitis C virus infection (age 58.0 +/- 11.8) were diagnosed with immune thrombocytopenic purpura. Platelet counts (x10(4)/mm3) were significantly lower in these 8 patients (2.9 +/- 2.1) than in chronic hepatitis C patients without immune thrombocytopenic purpura (16.7 +/- 0.3) (P<0.001). Hepatitis C virus infection predated immune thrombocytopenic purpura in 6 patients and none of the patients with immune thrombocytopenic purpura was infected with hepatitis C virus after the diagnosis. Three of the 6 patients with chronic hepatitis C, which predated immune thrombocytopenic purpura, were treated with interferon and 2 developed immune thrombocytopenic purpura after the treatment. None of them eradicated hepatitis C virus by interferon.

Conclusions: The fact that hepatitis C virus infection predated immune thrombocytopenic purpura in 6 of 8 patients suggests that hepatitis C virus could potentially induce immune thrombocytopenic purpura and interferon itself might induce immune thrombocytopenic purpura.