Thyroid dysfunction in thalassaemic patients: Ferritin as a prognostic marker and combined iron chelators as an ideal therapy

Abstract

Objective: Endocrine complications characterised patients with β thalassaemia (βT). In particular, thyroid dysfunction occurs frequently in βT major, but its long-term natural history is poorly understood. Design: A total of 72 βT patients were followed for 8 years. The incidence of thyreopathies, defined as the primary study endpoint, was assessed. The aim of this study was to analyse the prognostic role of ferritin for thyreopathies in patients with major and intermedia βT. The power of different iron chelators to treat iron overload and to prevent or reverse thyreopathies was also assessed. Methods: Patients were treated with chelators with different chelation strategies during the study. Receiver operating characteristics analysis was employed to calculate the area under the curve for serum ferritin to find the best cutoff values capable of identifying thyroid dysfunction in thalassaemic patients. Kaplan-Meier curves were generated to assess incidence of thyreopathy. Adjusted risk estimates for thyreopathy were calculated using univariate followed by multivariate Cox proportional hazard regression analysis. Results: Patients with thyroid dysfunction were characterised by higher ferritin when compared with patients without thyreopathies (1500(872-2336) vs 513 (370-698) μmg/l; P<0.0001). Patients with ferritin values above 1800 mg/l experienced a significantly faster evolution to endpoint (log-rank (χ2):7.7; P=0.005). Ferritin predicted high risk of thyroid dysfunction independently of confounding factors (hazard ratio: 1.20; P<0.0001). The intensification of chelation therapy led to an amelioration of thyroid function. Conclusions: Ferritin represents a prognostic marker for βT patients and a predictive factor for progression to thyroid dysfunction. Intensive chelation therapy allows the prevention and reversibility of thyroid complications. © 2013 European Society of Endocrinology.