Neonatal Thyroid Stimulating Hormone Screening as an Indirect Method for the Assessment of Iodine Status in Central Siberia

Abstract

Osokina Irina V

Background: Iodine deficiency is associated with goiter and impaired brain function. Neonatal thyroid-stimulating hormone (TSH) screening for congenital hypothyroidism used as an indicator of the degree of iodine deficiency and of its control. An increased frequency of thyroid-stimulating hormone (TSH) measurements above 5 mIU/L in newborn screening corresponds to the impaired iodine status of the population. The aim: to estimate the iodine deficiency and the effectiveness of iodine prophylaxis in Krasnoyarsk territory, Republics of Tuva and Khakassia according the results of neonatal TSH_screening.

Methods: An 18-year analysis was performed in 34,980 newborns participating in the national thyroid newborn screening program. The TSH concentration was measured in dry blood spots collected by heel stick on filter paper, 96 hours after birth, using DELFIA method.

Results: According to the data of the congenital hypothyroidism screening the rate of TSH < 5 mU/1 was 11.8% in Krasnoyarsk territory (23.9% in 2000) and corresponded to mild iodine deficiency. In different regions of Krasnoyarsk territory the rate of TSH < 5 mU/1 in the newborn varied from 3.5% to 23.7%. The highest values were marked in the Arctic peninsula Taimyr, in cities Zheleznogorsk (nuclear facility) and Sosnovoborsk, in Irbeysky, Suchobuzimsky, Eniseysky, Tuchtetsky, Novoselovsky regions (20.9–23.7%). In the Republic of Khakasia the rate of TSH < 5 mU/1 was 12.5%. In the Republic of Tyva the rate of TSH < 5 mU/1 was – 6.6% (38.6% in 1997; 11.5% in 2000). These results indicate mild iodine deficiency.

Conclusion: Our investigations show mild iodine deficiency in Central Siberia demanding continuous adequate iodine prevention. Additional assessment of the iodine intake in the regions with mild iodine deficiency is needed to prevent suboptimal cognitive and psychomotor outcomes.

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