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.

Thyroid hormones and thyroid autoantibodies, along with serum concentrations of two phytoestrogens of the isoflavone series, daidzein and genistein, were measured in 268 children without overt thyroid diseases, screened for iodine deficiency in one region of the Czech Republic. Since both phytoestrogens have been reported to inhibit thyroid hormone biosynthesis and in high concentrations to exert goitrogenic effects, we investigated whether their presence in the circulation could influence thyroid hormone function in a population where soy consumption is not common. Correlation analysis revealed a significant positive association of genistein with thyroglobulin autoantibodies and a negative correlation with thyroid volume. Multiple regression analysis of the relationships between actual phytoestrogen levels and measured thyroid parameters revealed only a weak but significant association between genistein and thyroid variables. Higher levels of free thyroxine were found in a subgroup of 36 children who ate soy food in the previous 24 h. In conclusion, only modest association was found between actual phytoestrogen levels and parameters of thyroid function. On the other hand, even small differences in soy phytoestrogen intake may influence thyroid function, which could be important when iodine intake is insufficient.

The relationship is shown between a concentration of urinary iodine and serum thyroglobulin in population studies carried out on a general population that was randomly selected from the registry of the General Health Insurance Company (individuals aged 6-98 years, 1751 males, 2420 females). The individuals were divided into subgroups with a urinary iodine concentration of <50, 50-99, 100-199, 200-299 and ≥300 μg/l. The mean and median of thyroglobulin were calculated in these subgroups. Tg concentrations were dependent on gender (males<females), age (thyroglobulin increased with age) and statistically significant negative relationship was observed between thyroglobulin and urinary iodine in individuals with urinary iodine <300 μg/l and the age under 65 years. Upper nonparametric tolerance limits of thyroglobulin in relation to iodine intake were calculated in subgroup of normal individuals (n=1858, thyroglobulin, urinary iodine, thyrotropin and free thyroxine were within the normal reference range). Upper limits were dependent on gender and age. The total value of upper limits is 44 μg/l; for individuals aged 6-17 years it is 39.1 μg/l; 18-65 years = 51.4 μg/l and 66-98 years = 60.6 μg/l. In general, thyroglobulin serum concentrations higher than 40 μg/l should be an indicator for determining urinary iodine.

Blood serum selenium of 65 men and hair selenium of 77 men from three regions of the Czech Republic (CR) were analyzed by neutron activation analysis, and 202 samples of urine from the same populations were analyzed for Se by the fluorimetric method to assess selenium status of these regions. Low status (53 micrograms Se/L of serum and 0.29 micrograms Se/g lyophilized hair as means) and very low urine selenium (8.7 micrograms/L urine) were detected. By these data, the CR is among the countries with the lowest Se intake. A comparison of studied regions is presented. Moreover, values of serum zinc were within the reference range, but mild to moderate deficiency in the supply of iodine was detected.

Autoimmune thyropathies are frequently linked to many infections, such as Helicobacter pylori, which are also supposed to play a role in their pathogenesis. The aim of this study was to evaluate the relationships between thyroid and gastric autoimmunity and H. pylori infection on a large sample of Czech population (n=1621) by monitoring the autoantibodies against thyroglobulin (anti-Tg) and thyroid peroxidase (anti-TPO) and gastric parietal cell (anti-GPC, representing thyrogastric syndrome) in correlation with antibodies against Helicobacter pylori (anti-H. pylori) of classes IgG and IgA. The interrelation between autoantibodies and H. pylori antibodies was assessed by H. pylori seropositivity. In H. pylori seropositive persons as compared to seronegative irrespective of age and sex, a higher occurrence of anti-TPO (10.4 % vs. 5.8 %, p=0.001) and anti-GPC (6.1 % vs. 1.7 %, p<0.001) was found. Differences in anti-TPO occurrence were significant in both men (7.0 % vs. 3.3 %, p=0.03) and women (12.7 % vs. 8.0 %, p=0.02), differences in anti-GPC occurrence were significant only in women (7.2 % vs. 1.7 %, p<0.001). Results of this study support the idea of a connection between infection of H. pylori and the occurrence of anti-TPO autoantibodies representing thyroid autoimmunity and gastric parietal cells autoantibodies representing the thyrogastric syndrome.