How to screen, evaluate and treat hypothyroidism in homozygous β-thalassemia (β-thal) patients

Abstract

Hypothyroidism denotes deficient production of thyroid hormone by the thyroid gland and can be primary (abnormality in thyroid gland itself) or secondary/central (as a result of hypothalamic or pituitary disease). The term “subclinical hypothyroidism” is used to define low grade primary thyroid gland dysfunction with mild increase of thyroid-stimulating hormone (TSH) concentration in the presence of normal serum free thyroxine (FT4). The diagnosis of hypothyroidism is primarily based on clinical symptoms and measurement of TSH and FT4 concentrations. In the general population, common causes of primary hypothyroidism are autoimmune thyroiditis as well as the consequence of therapeutic interventions, mainly thyroid surgery or radioiodine therapy. The pathophysiology of thyroid disorders in homozygous β-thalassemia (β-thal) patients is substantially different from that in healthy people. Body and organ iron overload are responsible for over 90% of morbidity and mortality in this population. Endocrinopathies are often managed by the caring physician. However, in more severe cases such as patients with insulin-dependent diabetes, adrenal insufficiency, disorders of gonadal hormones, hyperthyroidism or hypothyroidism, endocrine consultation for evaluation and prompt therapy is needed. This report summarizes the recommendations of the advisory members of the International Network on Endocrine Complications in Thalassemia and Adolescent Medicine (ICET-A) for the screening, diagnosis and treatment of hypothyroidism in patients with β-thalassemias. It is expected that these recommendations will foster the diagnosis and management of hypothyroidism in thalassemia communities and clinics for the benefit of the patients.