Heparin-induced hyperkalemia confirmed by drug rechallenge.

Subcutaneous heparin is commonly used as a prophylaxis against deep venous thrombosis in a wide variety of hospitalized patients. As with most medications, heparin has a significant side effect profile; heparin-induced hyperkalemia is an unusual but well described side effect. To increase awareness of heparin-induced hyperkalemia and of those patients at greatest risk, we present two cases of documented hyperkalemia induced by heparin and reconfirmed by drug rechallenge.