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Studies on the potential association of socioeconomic status with iodine supply and the risk for thyroid disorders from developed countries are sparse. Socioeconomic status, however, may particularly impact the efficiency of iodine prophylaxis programs, which are based on the voluntary principle. This study aims to investigate whether the socioeconomic status is cross-sectionally and longitudinally related to low urinary excretion or thyroid disorders in the population of northeast Germany.Data of the population-based Study of Health in Pomerania were used. The study population comprised 4056 adults for cross-sectional and 2860 adults for longitudinal analyses. Assessment of socioeconomic status comprised different scales of education, income, employment, and occupation. Thyroid-related outcomes included urinary iodine excretion, serum thyrotropin, and sonographically defined goiter and nodules. Statistical analyses were adjusted for confounders.Some of the socioeconomic variables were associated with thyroid-related characteristics in cross-sectional analyses. For example, there was an overall tendency for groups with higher education and higher income to have larger thyroid volumes and an increased risk of goiter. However, most of these associations did not attain statistical significance after correcting the target p-value for multiple testing. Longitudinal analyses did not demonstrate consistent results.Socioeconomic status neither substantially influences iodine supply nor does it have a major impact on the prevalence and incidence of thyroid deficiency-related disorders in the adult population of northeast Germany, indicating a good efficacy of the German iodine fortification program in all socioeconomic groups.

Monitoring of iodine fortification programs is required for early recognition of oversupply or ineffective supply with iodine. We investigated the potential role of selection bias for studies performed to monitor the iodine supply and prevalence of thyroid disorders.We used the baseline population of 3949 subjects recruited for the Study of Health in Pomerania as a hypothesized source population and associated the information on response behavior from the 5-year follow-up examinations with baseline sociodemographic and thyroid-related characteristics. Due to nonresponse, 649 subjects were lost. The 3300 follow-up respondents were divided into early and late respondents according to their recruitment level.We found no significant bias in the prevalence estimates of thyroid-related variables in the comparison between all respondents, and the source population after response maximization techniques had been applied. Prevalence estimates of thyroid-related characteristics (prior thyroid disorders, goiter, thyroid nodules, low serum thyrotropin, as well as increased and positive antithyroperoxidase [TPO] levels), however, were biased if we would have only investigated subjects who agreed to participate in our study after first invitation. When analyses were adjusted for sociodemographic variables, differences between early and late respondents were only statistically significant for positive anti-TPO levels.We conclude that selection bias likely influences prevalence data for some studies of thyroid epidemiology. This could be diminished by making invitation procedures more rigorous.

Serum ferritin levels are assumed to be an atherosclerotic risk factor. Ferritin production is increased in individuals with activated liver production, which has been shown in hyperthyroid conditions. An association between subclinical hyperthyroidism and serum ferritin levels would add an explanation to the relation between low serum thyrotropin levels and mortality. The aim of the present analysis was to investigate an association between thyroid function and serum ferritin levels. We hypothesized low serum thyrotropin to be related to high serum ferritin levels.The Study of Health in Pomerania (SHIP) is a population-based study comprising male and female adults aged 20 to 79 years. Data of 4111 subjects (2071 females) were available for the present analysis. Serum ferritin levels were determined by an immunoturbidimetric assay. Multivariable analyses were performed to investigate an independent relation between thyroid function and serum ferritin levels.Age-adjusted and gender-stratified analyses revealed no association between thyroid function and serum ferritin levels, neither in females nor in males. This finding remained stable after adjustment for potential confounders and in sensitivity analyses.There was no association between thyroid function and serum ferritin levels. We conclude that serum ferritin levels do not account for the relation between subclinical hyperthyroidism and vascular mortality.

An association between borreliosis and autoimmune thyroid disease (AITD) has previously been discussed. We undertook the present analyses to explore associations between anti-Borrelia immunoglobulin G (IgG) and AITD using data from the population-based Study of Health in Pomerania (SHIP), which was conducted in a region with endemic Borreliosis. Data of 4,256 persons were available for the present analyses. IgG antibodies to Borrelia were determined by enzyme-linked immunosorbent assay (ELISA). AITD was defined as the combined presence of a hypoechogenic thyroid pattern in thyroid ultrasound and positive anti-thyroperoxidase levels. An association between anti-Borrelia IgG and AITD was neither present in bivariate nor in multivariate statistical analyses. This result was not affected by using different definitions of the exposure and the end points. There is no association between the exposure to Borrelia as defined by anti-Borrelia IgG and the risk of AITD. It seems unlikely that Borrelia species represent a relevant causal factor for AITD.

We undertook the present study to establish reference data for serum thyroid function tests in a previously iodine-deficient area.Data from 4298 individuals, 20-79 years of age were available for the present analysis. Thyroid function (thyrotropin [TSH], free triiodothyronine [FT(3)], and free thyroxine [FT(4)]) and serum autoantibodies to thyroperoxidase (anti-TPOAb) were evaluated from blood samples. Thyroid structure and size were measured by ultrasound.A reference population was selected comprising 1488 persons (825 men) by excluding subjects with known thyroid diseases, and with yet unknown thyroid disorders such as goitre, inhomogeneous thyroid pattern, nodules, hypoechogenicity and anti-TPOAb seropositivity. Reference intervals for serum TSH, FT(3), and FT(4) were 0.25-2.12 mIU/L, 3.8-7.0 pmol/L, and 8.3-18.9 pmol/L, respectively. Reference serum TSH levels were not comparable to the reference values that were recently established for the U.S. population and most reference values slightly differed from the reference values provided by the manufacturers.The reference ranges of thyroid function tests in this formerly iodine-deficient region are distinct from the reference ranges that were established in areas with iodine sufficiency. Creating a reference population in the present setting should include thyroid ultrasound in order to exclude yet undiagnosed thyroid disorders.