DRUG-INDUCED THROMBOCYTOPENIA IS ASSOCIATED WITH INCREASED BINDING OF IGG TO PLATELETS BOTH INVIVO AND INVITRO

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  • 1 January 1981
    • journal article
    • research article
    • Vol. 58  (3) , 524-529
Abstract
Thrombocytopenia is a common adverse effect of drug treatment. A variety of in vitro diagnostic techniques to confirm the diagnosis are available but the majority lack sufficient sensitivity to detect all cases of drug-induced thrombocytopenia. Patients (19) with suspected drug-induced thrombocytopenia were studied, demonstrating that platelet-associated IgG (PAIgG) was elevated in all at the time of thrombocytopenia and returned to normal levels as the thrombocytopenia resolved. In the majority of patients, the platelet count rapidly returned to normal after the drug was discontinued; in 6 patients, thrombocytopenia persisted beyond the period of time that the offending drug would be expected to be cleared from the blood. In 13 patients, serum obtained after recovery was used to identify the drug responsible for the thrombocytopenia in an in vitro assay. In all cases, the addition of the drug historically associated with the thrombocytopenia episode was associated with an increased binding of IgG to control platelets. For uncertain reasons, the concentration of drug required to increase the in vitro binding of IgG to test platelets was often more than the concentration usually achieved in vivo. Wider application of these techniques may provide better understanding of the clinical characteristics and mechanisms responsible for drug-induced thrombocytopenia.