Context: Recently, reduced sensitivity to thyroid hormone as a more common finding in the general population and its possible association with metabolic parameters has been the focus of attention. Objective: The objective was to evaluate the cross-sectional association of thyroid hormone sensitivity with diabetes, metabolic syndrome (MetS), and its components. Methods: The study included a Tehranian representative sample of 5124 subjects aged ≥20 years participating in the Tehran Thyroid Study (2008-2011). Body weight, waist circumference, and blood pressure (BP) were measured, and serum concentrations of lipids and lipoproteins, fasting blood glucose, insulin, free thyroxine (fT4), and thyrotropin (TSH) were assayed. Thyroid hormone resistance was calculated by the Thyroid Feedback Quantile-based Index (TFQI) and Iranian-referenced Parametric TFQI (PTFQI) and compared with 2 other indices: Thyrotroph T4 Resistance Index (TT4RI) and TSH Index. Results: TFQI was significantly associated with high BP MetS criterion (OR = 1.14, 95% CI: 1.06, 1.23) and diabetes mellitus (OR = 1.16, 95% CI: 1.04, 1. 30, P = .009) in euthyroid subjects after adjusting for age, sex, smoking, physical activity, body mass index, and Homeostasis Model Assessment Index for Insulin Resistance. TFQI was not associated with new-onset diabetes contrary to known diabetes in subgroup analysis. The results were similar for PTFQI. TSHI (OR = 1.22, 95% CI: 1.08, 1.38, P = .001) and TT4RI (OR = 1.08, 95% CI: 1.01, 1.16, P < .001) were associated only with high BP in euthyroid subjects. Conclusion: The new TFQI index seems to be the indicator of reduced sensitivity to thyroid hormone most suitable to associate its population variations with diabetes and hypertension in euthyroid subjects; however, interpretation for diabetes should be concerned with cautions, necessitating future studies.

Context: The association between thyroid hormones within the euthyroid range and metabolic syndrome is not clear. Aim: This study evaluated the relationship between thyroid hormones and metabolic syndrome and its components in euthyroid subjects. Design and setting: This is a cross-sectional population based study conducted within the framework of the cohort of the Tehran Thyroid Study. Participants: Out of 5786 subjects aged ≥20 years, 3755 euthyroid subjects without a history of thyroid disorders, diabetes, or use of steroids or lipid-lowering agents were investigated. Outcome measures: Body weight, waist circumference (WC), and blood pressure (BP) were measured. Serum concentrations of lipids and lipoproteins, fasting blood glucose (FBG), insulin, free T₄ (FT₄), and thyrotropin (TSH) were assayed. Metabolic syndrome was determined by definition of the Joint Interim Statement adjusted for the Iranian population. Results: After adjustment for age, sex, and smoking, serum FT₄ was significantly associated with high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TGs), WC, systolic BP, and diastolic BP; the associations that remained significant after further adjustment for body mass index (BMI) and the homeostasis model assessment index for insulin resistance (HOMA-IR) except for HDL-C. Serum TSH was associated only with TGs after adjustments for age, sex, smoking, and BMI, an association that disappeared after further adjustment for HOMA-IR. Serum FT₄ was negatively associated (β=−0.02, 95% confidence interval [CI: −0.03, −0.01]) and TSH was positively associated (β=0.03 [CI: 0.01, 0.04) with insulin resistance. The prevalence of metabolic syndrome decreased from 30.1% in the lowest FT₄ tertile to 22.4% in the highest FT₄ tertile (p<0.001). The prevalence of other metabolic syndrome components decreased significantly from higher to lower FT₄ tertiles. Higher FT₄ values were associated with lower odds of metabolic syndrome (OR=0.96 [95% CI: 0.92, 0.99]; p=0.01). Conclusion: In euthyroid subjects, FT₄, rather than TSH, is associated with risk of metabolic syndrome and its components.

Introduction: Poorly treated or untreated maternal overt hyperthyroidism may affect pregnancy outcome. Fetal and neonatal hypo- or hyper-thyroidism and neonatal central hypothyroidism may complicate health issues during intrauterine and neonatal periods.Aim: To review articles related to appropriate management of hyperthyroidism during pregnancy and lactation.Methods: A literature review was performed using MEDLINE with the terms ‘hyperthyroidism and pregnancy’, ‘antithyroid drugs and pregnancy’, ‘radioiodine and pregnancy’, ‘hyperthyroidism and lactation’, and ‘antithyroid drugs and lactation’, both separately and in conjunction with the terms ‘fetus’ and ‘maternal.’Results: Antithyroid drugs are the main therapy for maternal hyperthyroidism. Both methimazole (MMI) and propylthiouracil (PTU) may be used during pregnancy; however, PTU is preferred in the first trimester and should be replaced by MMI after this trimester. Choanal and esophageal atresia of fetus in MMI-treated and maternal hepatotoxicity in PTU-treated pregnancies are of utmost concern. Maintaining free thyroxine concentration in the upper one-third of each trimester-specific reference interval denotes success of therapy. MMI is the mainstay of the treatment of post partum hyperthyroidism, in particular during lactation.Conclusion: Management of hyperthyroidism during pregnancy and lactation requires special considerations and should be carefully implemented to avoid any adverse effects on the mother, fetus, and neonate.

The aim of the current study was to determine the effect of a daily intake of three grams of cinnamon over eight weeks on glycemic indicators, advanced glycation end products, and antioxidant status in patients with type 2 diabetes. In a double-blind, randomized, placebo controlled clinical trial study, 44 patients with type 2 diabetes, aged 57 ± 8 years, were randomly assigned to take either a three g/day cinnamon supplement (n = 22) or a placebo (n = 22) for eight weeks. We measured the fasting blood glucose, insulin, hemoglobinbA1c, homeostasis model assessment for insulin resistance (HOMA-IR), carboxymethyl lysine, total antioxidant capacity, and malondialdehyde levels at the beginning and the end of the study. Thirty-nine patients (20 in the intervention group and 19 in the control group) completed the study. After an eight-week intervention, changes in the level of fasting blood glucose, insulin, hemoglobinbA1c, HOMA-IR, carboxymethyl lysine, total antioxidant capacity, and malondialdehyde were not significant in either group, nor were any significant differences between groups observed in these glycemic and inflammatory indicators at the end of the intervention. Our study revealed that cinnamon supplementation had no significant effects on glycemic and inflammatory indicators in patients with type 2 diabetes.

The impact of thyroid dysfunction in subclinical ranges on metabolic syndrome (MetS) is not well known. The aim of the present study is to evaluate the association of thyroid dysfunction with MetS and its components. In the cross-sectional population-based Tehran Thyroid Study, out of 5 786 randomly selected participants, aged≥20 years, subjects with thyroid nodules and cancer or any severe systemic disease, those who were pregnant and those using thyroid medication were excluded, leaving 5 422 subjects to be investigated. Body weight, waist circumference, and blood pressure were measured. Fasting blood glucose and concentrations of lipids and lipoproteins, free T4, and TSH were assayed. Mean age of the participants was 40.3±14.4 of whom 101 (2%) had overt hypothyroidism, 294 (5%) subclinical hypothyroidism, 82 (2%) overt hyperthyroidism, and 178 (3%) had subclinical hyperthyroidism; 1 704 (32%) had MetS. Clinically hypothyroid subjects had the highest prevalence of MetS (41.6%), abdominal obesity (45%), and hypertriglyceridemia (58%) compared to other groups (p50. Overt and subclinical hyperthyroidism had significantly higher odds of hyperglycemia in men and women after full adjustment for age, smoking, and BMI. Overt hypothyroidism and subclinical hypothyroidism especially in the elderly could be associated with MetS. Hyperthyroidism may induce hyperglycemia.

Thyroid peroxidase antibody (TPOAb), the most common antibody frequently measured in population surveys is a protein expressed in the thyroid gland. We conducted the present study to analyze the prevalence and incidence of thyroid auto immunity and natural course of TPOAb in a population based study. This prospective study was conducted within the framework of the Tehran Thyroid Study (TTS) on 5783 (2376 men and 3407 women) individuals aged ≥ 20 years who had thyroid function tests at baseline and were followed up for median 9.1 year with TPOAb measurements at approximately every 3 years. The mean age of total population at baseline was 40.04±14.32. At baseline, of the 5783 participants, 742 (12.8%) were TPOAb positive, with higher prevalence among women than in men (16.0 vs. 8.5%, p = 0.001). The prevalence of TPOAb positivity in the total population was 11.9, 14.9 and 13.6% in the young, middle age and elderly respectively. The total incidence rate (95%CI) of TPOAb positivity in the total population (5020) was 7.1 (6.36–7.98) per 1000 person-years of follow-up, with higher incidence of TPOAb positivity among young participants, i.e. 8.5 (7.5–9.7) per 1000 person-years. Sex specific incidence rate demonstrated that TPOAb positivity was higher in women, 9.3 (8.2–10.7) per 1000 person-years. The Cox's proportional hazard model analysis showed that the hazard ratio of developing TPOAb positivity was higher in women than men (P<0.0001) and tended to increase slightly with serum TSH levels (P<0.0001) but declined with increasing age (P<0.0001) in the total population. Our findings demonstrate that individuals, who became TPOAb positive in each phase, had significant elevation of TSH levels at the phase of seroconversion, compared to baseline values. Gender, age and elevated serum TSH were found to be risk factors for developing TPOAb positivity. Furthermore, compared to baseline a significant elevation of TSH levels during seroconversion phase was observed in TPOAb positive individuals.