Incidence of iodine deficiency in Turkish patients with congenital hypothyroidism

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Turkey is located in an area of mild to moderate iodine deficiency. The aim of the present study was to investigate the incidence of iodine deficiency in patients with congenital hypothyroidism. Twenty five patients with a median age of 12 days (6 days-6 months) at diagnosis and followed for a median time of 7 months (1-60 months) were enrolled in the study. Thyroid function tests, thyroid scintigraphy, ultrasonography and urine iodine measurements of the patients and mothers were performed. Congenital hypothyroidism was diagnosed within postnatal day 13, between days 13 and 30, and after 30 days of age in 68%, 20% and 12% of the patients, respectively. At the time of diagnosis mean serum thyroid-stimulating hormone and total T4 were 85.3 +/- 27.6 mIU/L and 3.9 +/- 2.8 microg/dL, respectively. Incidence of iodine deficiency was 36% in the patients (median, 110 microg/L) and 88% in the mothers (median, 40 microg/L). Thyroid scintigraphy and ultrasound were normal in all of the patients with iodine deficiency. At scintigraphic evaluation, thyroid gland was not visualized in 28% of patients; in the patients whose thyroid glands were not visualized scintigraphically thyroid ultrasonography indicated agenesis in 57%, and hypoplasia in 43%. In all the patients with thyroid agenesis or hypoplasia iodine levels were normal. In 36% of the patients imaging studies of thyroid gland and urine iodine measurements were normal. Despite salt iodization program, incidence of iodine deficiency is still high in patients with congenital hypothyroidism and mothers. National measures are urgently required for correction of iodine deficiency in Turkey.