High prevalence of thyroid dysfunction in adult patients with beta-thalassemia major submitted to amiodarone treatment

Amiodarone may induce hyper- or hypothyroidism. Patients with beta-Thalasse mia Major (beta-Thal) have an increased prevalence of primary hypothyroidis m and often require amiodarone for hemosyderotic cardiomyopathy. Aim of thi s study was to retrospectively evaluate thyroid function in beta-Thal adult patients on long-term amiodarone. The study group consisted of twenty-two (21 males, 1 female; age: 23-36 yr) beta-Thal patients submitted to long-te rm (3-48 months) amiodarone therapy from January 1991 to July 1996. Control s included 73 beta-Thal patients (23 males and 50 females aged 25-35 yr) no t treated with amiodarone. In all cases serum free thyroid hormones, thyrot ropin and thyroid autoantibodies were evaluated. A higher prevalence of ove rt hypothyroidism (5/22 [22.7%]) as compared to controls (3/73 [4.1%], p=0. 02) was found in beta-Thal patients less than or equal to 3 months after st arting amiodarone, while the prevalence of subclinical hypothyroidism was s imilar in amiodarone-treated (18.2%) and untreated (15%) beta-Thal patients . Overt hypothyroidism resolved spontaneously after amiodarone withdrawal i n 1 case, while the remaining patients were maintained euthyroid on amiodar one by L-thyroxine administration. After 21-47 months of amiodarone therapy , 3 patients (13.6%) developed thyrotoxicosis (2 overt and 1 subclinical), which remitted shortly after amiodarone withdrawal. No case of hyperthyroid ism was observed in beta-Thal controls (p=0.012 vs amiodarone-treated patie nts). In conclusion, amiodarone administration is often associated in adult beta-Thal patients to a rapid progression of the pre-existing subclinical hypothyroidism, but transient thyrotoxicosis may also be observed after a l onger period of therapy. These findings should be carefully considered in t he management of these patients. (J. Endocrinol. Invest. 22: 55-63, 1999) ( C)1999, Editrice Kurtis.