The Elimination of Iodine Deficiency in the Czech Republic: The Steps Toward Success

Abstract

The Czech Republic has a long history of iodine deficiency. Salt iodization was introduced in 1947, followed by a progressive correction of iodine deficiency. The present study reports the changes in the status of iodine nutrition and of thyroid function in the country from 1994 to 2002. The study included 29612 individuals, aged 0 to 98 years, including 5263 individuals randomly selected from the general population and 24349 individuals who attended the Institute of Endocrinology of Prague (hospital population). Urinary iodine was determined in all individuals. Measurements of serum thyrotropin (TSH), free thyroxine (FT4), free triiodothyronine (FT3), and thyroglobulin (Tg), were taken in 8544 to 19060 individuals. The iodine content of table salt was measured in 1130 samples. The median urinary iodine in the general and hospital populations were not significantly different. They progressively increased with time, starting from values indicating mild iodine deficiency (88-95 microg/L) prior to 1997, reaching the critical threshold of 100 microg/L in 1998, and optimal values between 120-140 microg/L since 2000. There was only a low and not significant positive correlation between the iodine content of salt and the urinary iodine. In contrast, urinary iodine showed marked seasonal changes, with the highest values during winter, when livestock were supplemented by mineral tablets containing iodine. Variables exploring thyroid function were all situated within the normal range in adults but another study (results not reported) has shown the persistence of slightly elevated TSH in neonates. The correction of iodine deficiency was not accompanied by unfavorable side effects. In conclusion, the Czech Republic has achieved sustainable elimination of iodine deficiency. Salt iodization has been a determining, but not the only, factor responsible for the success. Iodine supplementation of livestock and increased consumption of milk rich in iodine have probably played a determining role. Neonatal thyroid screening could constitute the major monitoring tool in order to insure sustainable elimination of iodine deficiency in the Czech Republic.

Universal screening detects two-times more thyroid disorders in early pregnancy than targeted high-risk case finding

“…The authors suggest that the former pattern may be related to iodine deficiency, while the latter to autoimmune thyroiditis (being also associated with TPO-Ab). Although iodine sufficiency was not specifically tested in our sample, we assume a generally satisfactory iodine status, as was recently demonstrated in our country in a population study using urinary iodine concentration and sonographically measured thyroid volume (30). Moreover, the thyroid volume in our sample (median 11 ml, interquartile range 9-13 ml) was not significantly different from that in the respective age and gender population subgroup (31).…”

Reference intervals in evaluation of maternal thyroid function during the first trimester of pregnancy

“…After that, with these intervals, the aim was to find the percentage of thyroid dysfunction in the population of pregnant women in the central portion of the Czech Republic. Iodized salt has been in regular use there since the 1950s, and a good level of iodine supplementation can be expected also based on the study by Zamrazil (22). We just do not know the exact iodine status of this study group.…”

Thyroid in Pregnancy

“…The recommended dietary allowance for nonpregnant, nonlactating women aged 14 year is 150 µg/d, for pregnant women is it 220 µg/d (Zimmermann & Delange, 2004),. In Czech Republic has been iodized salt in regular use since the 1950s, a good level of iodine supplementation can be expected also on Zamrazil study (Zamrazil, 2004). Women in this study were in addition supplemented by 100-150 ug of iodide daily.…”