Shock due to protamine hypersensitivity.

A 56-year-old man developed shock and skin flush minutes after the slow administration of 25 mg of protamine sulfate. Prior protamine exposure from treatment of his diabetes with isophane insulin (NPH insulin) was believed to have sensitized this patient to protamine. A review of three other cases of reaction to low doses of protamine revealed that in each, the patient had previously been exposed to protamine. If heparin is used in a patient with a history of treatment of diabetes with isophane insulin, the heparin should be allowed to spontaneously reverse, without pharmacological assistance if possible. If protamine must be used, the patient should be pretreated with glucocorticoid and vasopressors should be immediately available.