The results of population neonatal screening for congenital hypothyroidism reflect the effect of iodine prophylaxes in Belarus

Abstract

Primary congenital hypothyroidism (CH) is the most common neonatal metabolic disorder and before the introduction of neonatal screening programs it was one of the most frequent causes of mental retardation. CH has the incidence of about 1:3000 newborns in different populations. In Belarus the population neonatal screening for CH has been performing since 1991. By the beginning of 2010 1320580 newborns were screened, and 201 cases of CH were diagnosed. The frequency of CH was estimated as 1:6570. The most common cause of CH in Belarus is thyroid hypoplasia. Neonatal thyroid stimulating hormone (TSH) level is a sensitive marker of iodine deficiency, so the neonatal screening results can be used for monitoring the population iodine prophylaxes programs. In 90-th, the primary positive rate in neonatal screening for CH was 0.65–5.2% for different regions of Belarus with cut-off level of 25 mIU/L. TSH level >5 mIU/L was noticed in 50% of screened newborns. In the 21-th century the number of primary positives diminished to 0.01–0.02% with cut-off level of 15 mIU/L. TSH level >5 mIU/L is noticed in 8.9% of screened newborns. The results of population neonatal screening for CH reflect the effectiveness of iodine prophylaxes programs run in Belarus in the 21-th century.