A cross-sectional study of thyroid function, free thyroxine (FT4) and thyrotropin (TSH) concentrations, was carried out in 51 transfusion-dependent β-thalassemic patients receiving suboptimal iron-chelating therapy. Nine patients had normal FT4 levels with elevated TSH levels (5.9-15.6 mIU/L), consistent with the diagnosis of compensated primary hypothyroidism and giving a prevalence of abnormal thyroid function of 17.6%. All patients with abnormal thyroid function had negative thyroid antibodies. No particular risk factor for abnormal thyroid function could be identified. Of the nine patients with compensated primary hypothyroidism, one patient showed a further increase in TSH level after 1 year of follow-up. The results of the present study emphasize the importance of thyroid function monitoring in hypertransfused β-thalassemic patients.

Keywords: Hypothyroidism, Subclinical hypothyroidism, Thalassemia, Thyroid dysfunction