Prolonged thrombocytopenia associated with isotretinoin

OBJECTIVE: To report a case of severe prolonged thrombocytopenia possibly associated with isotretinoin. CASE SUMMARY: A 27-year-old white woman developed severe thrombocytopenia and elevated transaminases after 31/2 months of treatment with isotretinoin. Prior to the onset of thrombocytopenia, the patient had also received a 10-day course of cephalexin. Rectal bleeding was reported by the patient, who was otherwise asymptomatic. Liver enzyme values returned to normal approximately 1 week after discontinuation of isotretinoin; however, platelet counts required approximately 2 months to normalize. Based on the Naranjo probability scale, possible causality exists between isotretinoin and thrombocytopenia. DISCUSSION: The exact mechanism by which isotretinoin caused thrombocytopenia in this patient is not clearly understood. To our knowledge, only 3 previous cases of isotretinoin-associated thrombocytopenia have been reported. The long recovery process that occurred in our patient is possibly a direct result of the long elimination half-life of both the parent compound and active metabolites of isotretinoin. CONCLUSIONS: Clinicians prescribing isotretinoin should be aware of the potential life-threatening consequence of thrombocytopenia, and a complete blood cell count with platelets should be part of the routine monthly monitoring in all patients receiving isotretinoin therapy.