OTOTOXICITY IN HEMOGLOBINOPATHY PATIENTS CHELATED WITH DESFERRIOXAMINE

Purpose: Ototoxicity often limits the dose of desferrioxamine (DFO) to lerated by patients who are transfusion dependent. Current recommendat ions advise doses of < 50 mg/kg/day after early reports noted higher r ates of ototoxicity with increasing doses. There have been no follow-u p studies to determine the effect of this recommendation on ototoxicit y and iron overload. Methods: We followed 28 patients who were chronic ally chelated with serial audiograms over a 5-year period. Patients wi th and without ototoxicity were compared with respect to age, disease, DFO dose, peak DFO dose, length of DFO therapy, ferritin, and therape utic index. Results: Eight of the 28 patients (29%) had an abnormal au diogram during threshold testing. Two patients had two separate episod es with hearing deficit. Nine of the 10 episodes were high-frequency l osses, with seven being moderate and three mild. All deficits were rap idly reversible with DFO dose reduction. No significant differences we re found between the affected and unaffected groups with respect to ag e, DFO dose or duration, ferritin, or therapeutic index. Numbers of af fected patients were small, but patients with SCD differed from patien ts with thalassemia in that they developed ototoxicity earlier and wit h lower doses of DFO and lower therapeutic indexes. Conclusions: Despi te DFO doses usually felt to be low risk for ototoxicity, we found a h igh rate of ototoxicity in our patients who we've chronically chelated . No variables were identified that reliably predicted ototoxicity. We stress the need for regular audiological exams and feel no dose of DF O is ''safe'' from the development of ototoxicity.