Urinary Iodine and Genetic Predisposition to Hashimoto's Thyroiditis in a Chinese Han Population: A Case-Control Study.

Background: We aimed to examine the association of urinary iodine concentration with Hashimoto's thyroiditis (HT) risk, and particularly, to investigate whether the HT-related genetic variations might modify the effects of urinary iodine on HT in the Chinese Han population. Methods: We conducted a case-control study with 1723 Chinese (731 cases, 992 controls). The associations between urinary iodine concentration and HT risk were analyzed using logistic regression models. The effects of interactions between the genetic risk scores (GRSs) and urinary iodine on HT risk were assessed by including the respective interaction terms in the models. We also applied restricted cubic spline regression to estimate the possible nonlinear relationship. The multinomial logistic regression models were performed to determine the associations of urinary iodine with euthyroid-HT and hypothyroidism-HT. Results: After controlling for potential confounders, the odds of HT increased with increasing quartiles of urinary iodine concentration: adjusted odds ratios (ORs) and 95% confidence intervals [CIs] were 1.45 [1.06-1.99], 1.66 [1.17-2.34], and 2.07 [1.38-3.10] for the quartiles 2, 3, and 4, respectively, compared with the first quartile (p for trend <0.001). Multivariable restricted cubic spline regression analysis further demonstrated that there was a near-linear association between urinary iodine concentration and HT risk (p-overall <0.001; p-nonlinear = 0.074). However, we did not find significant interactions between urinary iodine and GRSs on the risk of HT (all p for interaction >0.05). Interestingly, we found that each increment of urinary iodine was associated with a more than twofold increase in the odds of hypothyroidism-HT (adjusted OR = 2.64 [CI = 1.73-4.05]), but not with euthyroid-HT (p > 0.05). Conclusions: Higher urinary iodine concentration was associated with increased risk of HT, and this association was near linear, indicating that increased urinary iodine has a continuous and graded impact on HT risk. Moreover, the iodine-HT association was not modified by genetic predisposition to HT. Interestingly, urinary iodine concentration was significantly associated with increased risk of hypothyroidism.

Correlation between iodine intake and thyroid disorders: a cross-sectional study from the South of China.

Great changes have taken place in the incidence of thyroid diseases since the implementation of universal salt iodization (USI). However, the high incidence of thyroid diseases caused by the high iodine intake has been contentious. The aim of this study was to investigate the relationship between iodine intake and thyroid diseases through the comparison of urine iodine concentration (UIC) between patients with thyroid diseases and healthy volunteers and to assess the status of iodine intake among the residents. From November 2013 to May 2014, 905 patients who underwent thyroid surgeries and 272 subjects of healthy controls were enrolled and were divided into two groups: the case group and the control group, respectively. Levels of thyroid hormones and thyroid autoantibodies in serum from blood were analyzed among all the patients. UIC and thyroid B ultrasounds were performed on each participant. The median urinary iodine (MUI) concentration was 184.5 and 169.6 µg/L for case group and control group, respectively (P = 0.003). Significant differences of the MUI were found between healthy controls and patients with Hashimoto's thyroiditis (MUI = 221.3 µg/L), nodular goiter (MUI = 193.5 µg/L), multiple nodules (MUI = 185.9 µg/L), nodule diameter ≥1 cm (MUI = 194.4 µg/L), hyperthyroidism (MUI = 258.7 µg/L), thyroid peroxidase antibody (TPOAb) (+), and thyroglobulin antibody (TGAb) (+) (MUI = 196.4 µg/L), and P values were 0.003, 0.000, 0.002, 0.000, 0.000, and 0.001, respectively. The susceptibility of the thyroid diseases among normal people was significantly associated with female sex (odds ratio (OR) = 3.3), older age (OR = 2.1), and high iodine intake (OR = 1.3). In conclusion, high iodine intake was likely to lead to the occurrence of thyroid diseases, such as Hashimoto thyroiditis, nodular goiter, and hyperthyroidism, through a long-term mechanism. USI should continue to be carried out and individual UIC detection was recommended for the disequilibrium of the iodine nutritional status among normal people.

Enhanced oxidative stress in Hashimoto's thyroiditis: inter-relationships to biomarkers of thyroid function.

OBJECTIVES: Oxidative stress has been implicated in the pathogenesis of several inflammatory and immune-mediated disorders including Hashimoto's thyroiditis (HT). The objectives of the present cross-sectional investigation were to estimate serum glutathione (GSH) status and the activities of its recycling enzymes in HT and to explore their interrelationships with biomarkers of autoimmunity and thyroid function. DESIGN AND METHODS: Newly diagnosed females with HT (n=44) and 58 matched control subjects were recruited. Thyroid hormone profile, anti-thyroperoxidase anti-body (TPO-AB), anti-thyroglublin antibody (Tg-AB), thyroid volume (Tvol), urinary iodine excretion (UIE), GSH and the activities of glutathione peroxidase (GPx), glutathione reductase and gamma-glutamyltransferase were assessed. RESULTS: Median UIE in HT was slightly but not significantly higher than that of controls. HT group exhibited higher levels of TSH, TPO-AB, Tg-AB and larger Tvol when compared with controls (P<0.001). The means of GSH and GPx in HT patients were significantly different from those of controls (P<0.001). In HT subjects, significant associations were seen between Tvol on TSH, GSH on TPO-AB, GSH on TSH and TPO-AB titers on TSH, respectively. CONCLUSIONS: This is the first study to demonstrate a substantial reduction in GSH status in HT subjects. Secondly, the interrelationship between the GSH contents and TPO-AB titers in HT provides a preliminary data to support the notion that GSH diminution is a hallmark of in the events leading to oxidative stress activation and the development of immunological intolerance in HT. Further studies are required to elucidate the role of GSH in the etiology of down-regulation of thyroid function.

The frequency of Hashimoto thyroiditis in children and the relationship between urinary iodine level and Hashimoto thyroiditis.

The aim of this study was to determine the frequency of thyroid autoimmunity in second grade primary school students and to examine the relationship between iodine and Hashimoto thyroiditis (HT). This was a cohort study performed with 1000 students. Urinary iodine levels, antithyroid peroxidase (anti-TPO) and antithyroglobulin (anti-Tg) antibodies were determined in all children. Children with anti-TPO or anti-Tg antibody positivity or with goiter were summoned for detailed examinations. In total, 36 cases (3.6%) were diagnosed as HT. The goiter frequency was found in 17.5% of the whole cohort. Additionally, iodine deficiency was found in 64.2% of all children. The median urinary iodine excretion was determined as 132 microg/L (range 382 microg/L) in the HT group, whereas it was 73 microg/L (range 390 microg/L) in children with goiter but without HT and 81 microg/L (range 394 microg/L) in normal children. The urinary iodine level of HT cases was significantly higher than the other two groups (p < 0.001). HT was also determined in 2% of patients with low urinary iodine levels, in 6.2% of patients with normal urinary iodine levels, and in 7.5% of patients with high urinary iodine levels. Our data demonstrates the close relationship between excessive iodine levels and autoimmunity.

Is neopterin level a predictive and differential biomarker in patients with thyroid disorders?

Neopterin production provides information about the extent of cellular immune activation. Measurement of neopterin levels may also provide predictive and prognostic information in patients with malignant thyroid diseases. In the present study, neopterin levels were investigated in patients with thyroid disorders (no.=68). Twenty-four patients had papillary thyroid cancers and the rest of them benign thyroid disorders. Results were compared with a healthy control group (no.=30). It was observed that there was a significant difference in neopterin levels between the control group and the thyroid disorders group (p<0.05). The mean neopterin levels in malignant and benign patients were also significantly different (p<0.05). Monitoring of urinary neopterin profile may be used in early diagnosis of papillary thyroid cancer. Neopterin seems to be a differential biomarker for malignant and benign thyroid disorders.

Comprehensive study of urinary cortisol metabolites in hyperthyroid and hypothyroid patients.

OBJECTIVE: To further analyse the significance and mutual relationship of thyroid function-linked alterations in cortisol metabolism that have been separately and variously reported. PATIENTS AND MEASUREMENTS: Twenty-four-hour urine samples from 21 patients with hyperthyroidism (Graves' disease), 16 patients with hypothyroidism (Hashimoto's thyroiditis), 21 healthy age- and sex-matched controls for hyperthyroidism, and 16 healthy age- and sex-matched controls for hypothyroidism were evaluated for 6beta-hydroxycortisol (6beta-OHF), tetrahydrocortisol (THF), tetrahydrocortisone (THE), allo-tetrahydrocortisol (allo-THF), urinary free cortisol (UFF), urinary free cortisone (UFE) and 17-hydroxycorticosteroid (17-OHCS). RESULTS: Urinary 17-OHCS, THE and allo-THF levels increased considerably in hyperthyroid patients compared to the controls, while UFF and THF showed no difference between the two groups. Urinary 6beta-OHF was significantly lower in the hyperthyroid patients than in the controls. Both the urinary allo-THF + THF/THE and the UFF/UFE ratios were significantly lower in the hyperthyroid patients than in the controls, whereas only the former was significantly higher in the hypothyroid patients than in the controls. The urinary allo-THF/THF ratio was significantly higher in the hyperthyroid patients and significantly lower in the hypothyroid patients than in the controls. In an analysis of pooled subjects including all groups (n = 64), free T4 levels correlated negatively (P < 0.0001) with the urinary allo-THF + THF/THE ratio but not with the UFF/UFE ratio. The serum levels of free T4 correlated positively (P < 0.0001) with the urinary allo-THF/THF ratio. CONCLUSION: The thyroid hormones seem to affect the total 11beta-HSD activity (allo-THF + THF/THE) more strongly than the renal 11beta-HSD2 activity (UFF/UFE). 5alpha-reductase activity (allo-THF/THF) is also enhanced in hyperthyroidism, while the reduction of urinary 6beta-OHF in hyperthyroidism might be a secondary effect of the altered activity of the total 11beta-HSD and 5alpha-reductase.