Purpose: A case of probable carvedilol-induced thrombocytopenia is reported.
Summary: A 64-year-old African-American woman with a history of hypertension, diastolic dysfunction, mild left-ventricular hypertrophy, and pulmonary embolism was hospitalized with a platelet count of 94,000 platelets/mm(3). Dalteparin, warfarin, and carvedilol had recently been added to her medication regimen. Beta-2-glycoprotein immunoglobulin G (IgG) antibody, anticardiolipin IgG, and anticardiolipin immunoglobulin M tests, conducted to rule out antiphospholipid syndrome, revealed values within the normal range. After the exclusion of dalteparin, hydrochlorothiazide, and other causes of drug- and non-drug-related thrombocytopenia, carvedilol was discontinued and replaced with metoprolol tartrate. After this substitution, the patient's platelet count continued to rise. On hospital day 10, the patient was discharged to home on low-molecular-weight heparin bridging therapy, warfarin sodium 5 mg orally daily, ranitidine 150 mg orally daily, metoprolol tartrate 75 mg orally twice daily, lisinopril 20 mg orally daily, amlodipine 10 mg orally daily, cyanocobalamin 1000 mg orally daily, and two tablets of hydrochlorothiazide 25 mg-triamterene 37.5 mg orally daily. Her platelet count was 319,000 platelets/mm(3) on the day of discharge and remained stable thereafter. The recovery time of the platelets coincided with the elimination half-life of carvedilol.
Conclusion: A woman developed thrombocytopenia, first noticed as a reduction in the platelet count to a low-normal value, 17 days after treatment with carvedilol was begun. Other possible culprit drugs were withdrawn, but the platelet count continued to drop until carvedilol was discontinued. The platelet count rose on the day of carvedilol removal and was within the normal range within another day.