High prevalence of central hypothyroidism in adult patients with β-thalassemia major.

The commonest form of thyroid dysfunction seen in subjects with TM is primary hypothyroidism due to abnormalities of the thyroid gland. Central hypothyroidism (CH) has been reported as an uncommon clinical entity in TM patients although the anterior pituitary gland is particularly sensitive to free radical oxidative stresses. Diagnosis is usually made on a biochemical basis showing low circulating concentrations of thyroid hormone associated with an inappropriately low TSH levels. The diagnosis is not clinically obvious and a basal normal TSH level does not exclude the diagnosis of CH. Therefore, it is important that clinicians accurately interpret thyroid function tests. In TM patients, CH prevalence differs at different ages is unknown and it is not easy to diagnose because most of the symptoms of symptoms of CH are non specific and are frequently attributed to anaemia or other associated complications . We performed a cross-sectional analysis on a large database using the clinical records of our TM patients to explore the prevalence of CH in prepubertal (<11 years: 25 patients; 13 males) peripubertal (between 11 and 16 years: 9 patients; 3 males), and pubertal TM subjects (>16 years: 305 patients; 164 males). Central hypothyroidism was present in 26 (7,6%) TM patients. Their mean age was 29.9 ± 8.4 years, 14 (53.8%) were males and 12 (46.1%) were females. The prevalence of CH was 6% in patients with a chronological age below 21 years and 7.9% in those above 21 years. Clinicians should be alert for the diagnosis of CH through accurate interpretation of thyroid function tests. We recommend L-thyroxine therapy if the level of FT4 is consistently low provided that the patient has normal cortisol levels.