Thrombocytopenia with Sodium Cephalothin Therapy

Thrombocytopenia occurred on two separate occasions in a patient while she was receiving sodium cephalothin. After recovery, a test dose of cephalothin (1 g) produced a 50% drop in the platelet count. A month later a survival study of 51Cr-labeled autologous platelets was normal. During the survival study a 1-g infusion of cephalothin produced a rapid disappearance of platelets and accelerated loss of radioactivity. In vitro studies showed a specific anticephalothin antibody in the patient's serum. When cephalothin was added in vitro to the patient's platelets, her serum agglutinated these coated platelets but not her own uncoated platelets. This activity could be neutralized by prior incubation of the serum with cephalothin. A second patient with cephalothin-induced thrombocytopenia had similar in vivo results with unlabeled platelets. These studies suggested the production of a specific antibody that binds to cephalothin-coated platelets and results in a shortened platelet survival and thrombocytopenia.