Endocrine Abstracts

Introduction: Short stature and hypothyroidism and are frequent complications of thalassemia major (TM).

Patients and methods: We recorder growth parameters and investigated the thyroid function in TM patients attending our Pediatric Endocrine Clinics for 12 years. Definitions: overt hypothyroidism (low FT₄ and increased TSH levels >5 μIU/ml); subclinical hypothyroidism (normal FT₄, TSH between 5–10 μIU/ml) and central (secondary) hypothyroidism (low FT₄ and normal or decreased TSH).

Results: 48 patients completed a 12 years of follow-up. Hypothyroidism was diagnosed in 35% of patients without gender difference. There was a progressive decrease of height SDS (from −0.2±0.3 to −1.78±0.5) and BMI SDS (from 0.2±0.3 to −0.6±0.35). HtSDS was <−2 in 46% of patients. The general trend of free thyroxine level showed progressive decrease over the 12 years, whereas TSH levels did not show a corresponding increase. 94% patients had hypothyroidism after the age of 10 years. Overt hypothyroidism had risen from 0% at the age of 7 years to 35% at the age of 18 years. None had high anti-thyroperoxidase (TPO) antibody titers. 13/17 patients with hypothyroidism, had normal or low TSH level (not appropriately elevated) indicative of defective hypothalamic pituitary response to low FT₄ (central hypothyroidism). 3/17 patients had subclinical hypothyroidism (TSH between 5 and 10 μIU/ml and normal FT₄). There was a significant negative correlation between serum ferritin and FT₄ (r=−0.39, P=0.007) and between FT$ and HTSDS (r=0.52, P<0.001).

Conclusions: Progressive height loss and worsening of thyroid function was observed in 46 and 35% respectively in thalassemic patients by the age of 18 years. The lack of proper increase of TSH in response to low levels of FT₄ in (76%) of these patients indicated a high incidence of defective pituitary thyrotrophic function in these patients.