thyroid function

Selenium, a trace element present in specific selenoproteins, is essential for thyroid hormone metabolism. Selenium is also an antioxidant with immunosuppressive properties and may help in managing thyroid autoimmune diseases, including Graves’ (GD) hyperthyroidism and Graves’ ophthalmopathy (GO). There were 320 clinical studies related to selenium and thyroid published in English and French between January 1, 2000, and June 1, 2023. Our focus was to identify studies reporting levels of serum selenium in patients with GD and studies that assessed the effect of selenium supplementation on outcomes of GD hyperthyroidism and GO. We also reviewed 20 systematic reviews and meta-analyses of randomized controlled trials that reported selenium levels in GD and the effects of supplementation on GD and GO outcomes. Our review showed that patients with GD had serum selenium levels lower than those of various control patients. In the short-term, a selenium supplement to antithyroid drugs showed benefit for GD hyperthyroidism in most studies, but long-term benefits and positive effects on remission rate were unclear. Some studies did not show benefit. The benefits may depend on baseline selenium deficiency. Two randomized controlled trials showed positive effects of supplementation for mild GO; however, studies about moderate and severe GO are still needed. There is evidence for benefit with short-term selenium supplementation for GD hyperthyroidism, but controlled studies are needed to assess long-term benefits, and benefits in selenium-sufficient areas.

Hydrocarbons (benzene, toluene, ethyl benzene and xylene (BTEX) found in gasoline and organic solvents are ubiquitous in the environment, and are known to have toxic effects in human system. This study therefore investigated the thyroid function of workers occupationally exposed to gasoline and paint products using TSH, T3 and T4 as markers. A total of 162 subjects were recruited for this study; (56 gasoline pump attendants and 56 paint factory workers) and 50 subjects as control. Blood sample was collected from each subject and thyroid function tests (T3, T4 and TSH), were assayed using Enzyme linked immunosorbent assay (ELISA) techniques. The mean values of TSH was significantly lower in the gasoline workers and painters compared to the control subjects (1.73±0.89, 1.66±0.84 Vs 2.09±1.06µIU/ml; F= 3.169, p<0.05). The mean values of T4 was significantly lower in gasoline workers and painters when compared to the control subjects (9.09±1.87, 9.63±1.90 Vs 12.06 ± 1.82µg/dl; F= 37.430, p<0.05). However, the mean levels of T3 was significantly higher in gasoline workers and painters compared to the control subjects (2.56± 0.65, 2.72 ± 0.65 Vs 1.03 ± 0.30ng/ml; F= 161.292, p<0.05). The mean body mass index, systolic and diastolic blood pressures were similar in all the groups. The levels of TSH showed a significant inverse correlation with the duration of exposure in the subjects exposed to gasoline (r=-0.326, p<0.05), whereas the levels of T3 showed a positive significant correlation with the duration of exposure in paint workers (r=0.301; p<0.05). This study demonstrated that both gasoline and paint showed similar effects on the thyroid parameters of the subjects under study, which is suggestive of T3 thyrotoxicosis.

Chronic kidney disease (CKD) is a rising public health concern that has detrimental effects on cardiovascular health and overall survival. Subclinical hypothyroidism (SCH) has been associated with poor outcomes in the general population. It is thought to be more prevalent in CKD subjects, and their coexistence may contribute to poor outcomes in these patients. We aimed to determine the prevalence of SCH in CKD.

Using data from the Tehran thyroid study, which is a prospective population-based cohort study, adult subjects with an estimated Glomerular Filtration Rate (eGFR) of 60 mL/min/1.73 m2 or less were selected for studying the prevalence of thyroid abnormalities, as well as other known cardiovascular risk factors.

Of 5,626 subjects recruited, 823 (14.6%) individuals had CKD. Individuals with CKD were older, heavier, had a higher prevalence of diabetes, higher serum thyrotropin, and thyroid peroxidase anti-body levels, but lower free thyroxine levels. The prevalence of SCH was 7.3% and 5.2% (P < 0.001) in kidney disease and non-kidney disease subjects, respectively. However, there was no difference in the risk of SCH between CKD and non-CKD subjects after adjustment for age, sex, BMI, smoking, and TPOAb (OR: 1.28; 95%CI, 0.89 - 1.83). None of the metabolic markers compared between the CKD subgroups of those with and without SCH remained statistically significantly different after adjusting for age and gender.

The prevalence of SCH was not higher in CKD after controlling for confounding factors. Besides, CKD subjects with and without SCH had no different metabolic parameters.

To evaluate the recommendations on the most adequate screening method (universal or selective) for thyroid dysfunction. Although thyroid dysfunction is a common disorder in fertile women and untreated cases may have negative maternal, fetal and neonatal outcomes, its screening in preconception and early pregnancy is controversial.

An evidence-based review was conducted to identify publications since 2017 of American Thyroid Association (ATA) guidelines, according to the following Population, Intervention, Comparison, Outcomes and Study (PICOS): women in preconception or pregnancy without thyroid disease who underwent universal or selective screening for thyroid dysfunction. Study selection obeyed the PRISMA criteria.

We included 15 of 325 publications. The 2017 ATA guidelines recommend selective screening in both preconception and pregnancy. The only two reviews on preconception recommended universal screening. For pregnancy, nine articles suggested universal screening, while a prospective study advocated selective screening. The main benefits advocated for universal screening were easy and low-cost tests; absence of missed diagnosis; safe and inexpensive treatment and its potential in preventing negative outcomes. Iodine deficiency is a decisive indication, but it was not evaluated in all clinical studies. Screening harms and knowledge gaps were the main arguments against universal screening. There are very few cost-effectiveness studies.

We recommend universal screening for thyroid dysfunction in early pregnancy, which is a distinct point of view from 2017 ATA guidelines (weak recommendation, low-quality evidence). It is not possible to make a formal recommendation for preconception (insufficient evidence). We strongly suggest an individualized analysis by each country.

In this study, thyroid dysfunction in women with gestational diabetes mellitus was examined and compared to that in healthy pregnant women referred to Kowsar Hospital in Qazvin in 2017 and 2018.

In this case-control study, 100 women with gestational diabetes mellitus and 100 non diabetic healthy pregnant women who referred to Kowsar Hospital in Qazvin from 2017 to 2018 were selected using the convenience sampling method, and their serum thyroxine, anti-TPO, and TSH levels were determined and compared. Moreover, Apgar scores and anthropometric variables were compared between the two groups.

In the present study, there were statistically significant differences between the groups in terms of the TSH level (P=0.012), assessed by the independent t-test, the thyroxine (P=0.0001) and anti-TPO (P=0.008) levels, both examined by the Mann-Whitney test, which associated with high levels of TSH and anti-TPO and low levels of thyroxine in the diabetic group. No differences were found regarding the Apgar scores and anthropometric variables between the groups (P>0.05).

Overall, according to the obtained results, it can be inferred that thyroid dysfunction, realized as hypothyroid with high anti-TPO levels, was more prevalent in women with gestational diabetes mellitus compared to healthy pregnant women.