Thrombotic Microangiopathy, Hemolytic Uremic Syndrome, and Thrombotic Thrombocytopenic Purpura Following Hump-nosed Pit Viper (Genus: Hypnale) Envenoming in Sri Lanka

Thrombotic microangiopathy (TMA), which includes the spectrum of hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, is an uncommon complication of hump-nosed pit viper envenomation. We describe 4 cases of TMA following hump-nosed pit viper (Hypnale spp) bites in Sri Lanka. The first case is a typical TMA that spontaneously resolved with supportive treatments. The second and third cases are related to hemolytic uremic syndrome complicated with acute kidney injury that required hemodialysis. The fourth case is thrombotic thrombocytopenic purpura associated with acute kidney injury that required hemodialysis and therapeutic plasma exchange. For each patient we describe the circumstances of the bite, clinical features, laboratory findings, and management.