Some aspects of thyroid dysfunction in thalassemia major patients with severe iron overload

Background Severe iron overload due to recurrent transfusions for chronic anemia and inadequate iron chelation therapy in thalassemia major patients result in various complications, including hypothyroidism. Currently, there has been no data on the prevalence of hypothyroidism in thalassemia major patients at the Thalassemia Centers, Department of Child Health, Cipto Mangunkusumo Hospital (DCH CMH). Objective To study the prevalence of primary hypothyroidism in thalassemia major patients in the Thalassemia Center, DCH MCH. Methods We performed a cross-sectional, descriptive study. All thalassemia major subjects aged 0-18 years with severe iron overload underwent thyroid function examination. Primary hypothyroidism was defined as either normal (compensated) or decreased (decompensated) free T4 (FT4) levels, along with elevated sensitive thyroid-stimulating hormone (TSH) Results 179 subjects enrolled this study with male: female ratio of 1:1.6. The prevalence of primary hypothyroidism in thalassemia major patients with severe iron overload was 26.8% (48/179). Of those 48, 45 had compensated hypothyroidism and 3 had decompensated hypothyroidism, 25.1% and 1.7% of the total subjects, respectively. Compensated hypothyroidism was observed in 17 subjects aged <10 years and in 28 subjects aged >10 years. All 3 decompensated hypothyroidism cases were > 10 years of age. No relationship was found between the occurrence of primary hypothyroidism and mean pre-transfusion Hb levels (P=0.481, OR 1.30; 95% CI 0.63 to 2.68), elevated serum ferritin levels (P-0.74, OR a89; 95% CI 0.46 to L75), and compliance to iron chelation therapy (P=0.570, OR 0.76; 95% CI 0.35 to 1.65). Based on multivariate analysis, only age of < 10 year-old (P=0.029, OR 0.469; 95% CI 0.23 to 0.93) was significantly associated with primary hypothyroidism. Further analysis using receiver operator curve (ROC) technique found that age of 8.5 year-old was the cutoff value to predict the risk of hypothyroidism. Conclusion The prevalence of primary hypothyroidism in our study is high. The occurrence of hypothyroidism is associated with age.