Hypothyroidism in patients with thalassemia syndromes.

Sixty transfusion-dependent thalassemic patients were studied by simultaneous measurement of circulating thyroid hormones, basal thyroid-stimulating hormone (TSH) and TSH response to thyrotropin-releasing hormone with the aim of evaluating the frequency of hypothyroidism in such patients, and the relationship between hypothyroidism and compliance with treatment and iron overload. Thyroid failure was present in 31 of the 60 patients. A correlation was found between impairment of thyroid functions, duration of chronic hypoxia and the activities of various transaminases. The results of this study emphasize the importance of early evaluation of thyroid function in thalassemic patients and suggest that anemia and hypoxia may potentiate the toxicity of iron deposition in endocrine glands.