Endocrine Abstracts

Introduction: Thyroid function is commonly impaired in β-thalassemic patients with an estimated prevalence of hypothyroidism of 9–11%. According to literature, iron overload is the main cause of tissue damage involving both thyroid and pituitary gland, thus leading to primary or secondary hypothyroidism respectively. However, thyroid morphology has been rarely investigated in adults. The aim of this study is to evaluate thyroid volume (TV) and thyroid morphology in β-thalassemic adult patients compared to healthy controls.

Methods: We performed a cross-sectional, controlled study in 13 β-thalassemic adult patients (six males and seven females) (36.36±4.26 years) and 120 healthy volunteers (28 males and, 92 females) (38.1±4.9 years). All subjects underwent thyroid ultrasonography performed by the same operator. TV was calculated as the sum of the volume of the two lobes, each estimated by standardized formula: length×width×depth×0.479. Ultrasound evaluation included the presence/absence of hypoechogenicity and echotexture heterogeneity, and the presence/absence of nodules.

Results: TV was significantly lower in β-thalassemic patients (5.41±1.33 ml) than in the control group (8.45±2.81 ml) (P<0.001) independently from their thyroid function (euthyroidism or hypothyroidism). The prevalence of diffuse echotexture heterogeneity and hypoechogenicity of the thyroid was significantly higher in thalassemic patients (92.3%) than in the control group (42.4%) (P<0.001). Thyroid antibodies were negative in all thalassemic patients. Thyroid nodules were found in four thalassemic patients (30.7%) and in 44 volunteers (36.7%) (P=0.674).

Discussion: In adult β-thalassemic patients TV was smaller than in healthy subjects even when patients with a normal thyroid function were considered. Moreover the prevalence of hypoechogenicity and echotexture heterogeneity, without a confirmed diagnosis of autoimmune thyroiditis, was higher. These results suggest a primary thyroid damage, characterized by thyroid hypoplasia and tissue alterations probably caused by iron infiltrates. Furthermore, the risk of developing thyroid nodules seems not to be increased in beta-thalassemic patients.