The results of neonatal TSH screening do not agree with indicators of the optimal iodine status of pregnant women in the Republic of Georgia

Abstract

Background. Georgia historically was a country with moderate to severe iodine deficiency and high prevalence of endemic goiter. A representative countrywide iodine survey conducted in Georgia in 2017 confirmed optimal iodine nutrition of the population with median UIC 298 mcg/L in SAC and 211 mcg/L in PW. Aim. The aim of this study was to assess status of iodine nutrition of population in Georgia. Methods. The assesement based on the proportion of neonatal Thyroid-Stimulating Hormone (TSH) levels >5mIU/L from 2009 to 2015 and compare these data with the results of direct assessment of iodine status made during the 2017 national survey. Results. From 2009 to 2015 the proportion of newborns with TSH >20 mIU/L decreased threefold: from 0.45 to 0.15%. This trend was observed in all regions of the country with significant difference between the capital city and Western in Eastern parts of the country. There has been also significant reduction of the prevalence of TSH >5 mIU/L in Georgia from 4.46% in 2009 to 3.5% in 2015. However, only in Tbilisi the frequency of elevated TSH was below 3% – the cutoff level for adequate iodine nutrition. In other regions (Western and Eastern Georgia) prevalence of TSH >5 mIU/L was 3.8% and 4.4% respectively that could be falsely interpreted as mild iodine deficiency. Conclusions. Although neonatal TSH is useful to detect moderate to severe iodine deficiency, it should be cautiously recommended for the evaluation of iodine status in iodine sufficient to mildly iodine deficient regions.