لادن مهران

 To overcome the limitations of the definition of metabolic syndrome (MetS) in clinical use, a health index named quantitative Metabolic Syndrome Severity Score (cMetS-S), has been recently introduced and validated in the Tehran Lipid and Glucose Study. This study investigated the association between the severity of MetS based on age and gender (cMetS- score), and cardiovascular diseases (CVD) beyond the components of MetS.

 At the beginning of the study, participants aged 20-60 years were enrolled. Those with cardiovascular disease, cancer, use of corticosteroid, estimated glomerular filtration rate <30 ml/min/1.73m², or pregnancy were excluded. The association between cMetS-S and cardiovascular diseases was evaluated continuously for 18 years follow-up among 8,500 participants using Cox proportional hazards regression models and its performance in predicting cardiovascular disease events was compared with the MetS criteria.

 Participants with higher cMetS-S showed a significant increase in the risk of cardiovascular disease (CVD), coronary heart disease (CHD), and non-coronary heart disease (non-CHD). Independent of the confounding factors of metabolic syndrome components, each 1-SD unit increase in cMetS-S was associated with risk ratios of 1.67, 1.60 and 1.88 for cardiovascular diseases, coronary and non-coronary cardiac events, respectively. Model fit analysis showed better CVD prediction value for cMetS-S independent of (MetS) components, compared with metabolic syndrome (p<0.0001).

 The cMetS-S predicts cardiovascular diseases more accurately than the MetS and its components. The standardized cMetS-S, which considers the weighted contribution of MetS components and their variations by age and gender, may serve as a health metric for determining the severity of metabolic syndrome.

Thyroid dysfunction can impair fat and glucose metabolism, blood pressure, and body weight. On the other hand, metabolic syndrome (MetS) can be associated with an increased risk of hypothyroidism. Due to the high prevalence of both disorders and the possibility of synergistic metabolic detrimental consequences in combination, this review study aimed to investigate the reciprocal association between thyroid function and MetS.

Articles in PubMed and Web of Science written in English were searched from 1991 to 2021 using search terms hypothyroidism, hyperthyroidism, thyroid hormones, thyroxine, thyroid-stimulating hormone, and metabolic syndrome in titles and abstracts.

Hypothyroidism and even changes in thyroid hormones within the normal range are associated with disorders of various metabolic risk factors; however, the risk of developing MetS in people with both euthyroidism and subclinical hypothyroidism remains a controversial issue. Hyperthyroidism may be associated only with insulin resistance and impaired blood sugar levels (dysglycemia). Although the effect of various metabolic disorders such as obesity and diabetes on thyroid function has been observed, the results are contradictory regarding the prevalence and incidence of thyroid dysfunction in patients with MetS and healthy individuals.

The association between MetS, thyroid function, and thyroid hormones is reciprocal and complex and may be affected by age, gender, insulin resistance, smoking, iodine intake, and inflammatory markers.

Physiological changes during pregnancy affect thyroid function and also free thyroxine (FT4) assay methods. These impacts make immunoassays unreliable for detecting hypothyroxinemia during pregnancy. Due to pregnant women’s adequate consumption of iodine in Iran, reference ranges of FT4 needs to be obtained for this group.

A total of 1077 Iranian pregnant women were randomly selected from health clinics in 12 provinces of Iran during all trimesters. Five hundred eighty-seven individuals were included in the study after applying the exclusion criteria to establish the reference range. Then, TSH, FT4, and TPOAB levels were examined.

The mean age of the participants was 27.6 ± 5.7 years, and the median urine iodine level was 236 μg/L (188-321). The 5th and 95th percentiles obtained for FT4 were 0.93 and 1.35 in the first trimester, 0.78 and 1.15 in the second trimester, and 0.77 and 1.15 ng/dl in the third trimester, respectively.

Due to the downward trend of the normal range of FT4 from the first to the third trimester of pregnancy, it seems necessary to consider the trimester-specific normal range for diagnosis and management of thyroid disease in Iranian pregnant women.

The prevalence of overweight and obesity is alarmingly rising around the world. With the increasing prevalence of obesity, study of thyroid disorders, caused by an abnormal increase in the body mass index (BMI), is becoming more and more important. This study aimed to evaluate the association between increased BMI and thyroid hormones among Iranians participating in the Tehran Thyroid Study.

This cross-sectional study was conducted on 3079 female and 2274 male participants, who were categorized into two groups: one with abnormal BMI>25 kg/m2 and the other with normal BMI<25 kg/m2. Thyroid hormone levels were also evaluated and compared. The linear regression analysis and Spearmanchr('39')s coefficient test were used to determine the correlations between BMI and thyroid hormones. The odds ratio (OR) and 95% confidence interval (CI) were measured to study the impact of obesity on thyroid function.

BMI had a positive correlation with the thyroid-stimulating hormone (TSH) level (r=0.04, 95% CI: 0.01, 0.07; P<0.05) and a negative correlation with the free thyroxine (FT4) level (r=-0.18, 95% CI: -0.21, -0.16; P<0.05). Also, BMI above 25 kg/m2 was associated with a higher OR of clinical hypothyroidism (OR=1.71, CI: 1.04, 2.79; P<0.05). No significant association was observed between abnormal BMI and other thyroid dysfunctions. Also, no significant association was found between an abnormal increase in BMI and TPOAb positivity in the adjusted results.

This study showed that an abnormal increase in BMI was associated with altered thyroid functions. Consequently, weight control and reduction can be suggested to individuals with overweight and obesity to improve their thyroid function.

Neonatal hypothyroidism, a preventable cause of mental retardation, has a high prevalence in Iran. Considering the high prevalence of the transient form of this disease, which recovers within 4-6 months after birth, it is important to determine factors that can differentiate between permanent and transient hypothyroidism in Iran.

In this retrospective cohort study, neonates born in 15 selected provinces of Iran in 2011 were included. The evaluated information in this study included cumulative data, routinely collected in the national screening program for congenital hypothyroidism.

A total of 598 (57.1%) infants were diagnosed with permanent congenital hypothyroidism, and 449 (42.9%) infants were diagnosed with transient congenital hypothyroidism. Based on the ROC curve analysis, serum thyroid-stimulating hormone (TSH) levels ​​above 20 mU/L predicted permanent cases with 75.2% sensitivity and 82% specificity. Also, serum thyroxine (T4) levels below 8.2 μg/dL predicted permanent cases with sensitivity of 72.1% and specificity of 64%. Overall, a serum TSH level ≥20 mU/L, a serum T4 level ≤8.2 μg/dL, parental consanguinity, and family history of thyroid diseases increased the risk of permanent hypothyroidism, respectively.

The serum levels of T4 and TSH are the most important prognostic factors for the prediction of permanent congenital hypothyroidism. Although it is not possible to make a definitive early diagnosis, we may be able to differentiate the transient form more quickly, with greater sensitivity and specificity, by conducting larger studies and advanced modeling; this would help medical teams discontinue long-term treatments for transient cases and reduce the financial and emotional burdens on families.

Iodine deficiency disorder, (IDD), is a worldwide health problem. Parts of Iran, such as Semnan, are known as endemic areas for goiter. IDD was accepted as a priority health problem in our country and a National IDD Council was formed in 1989. This study was performed to evaluate the implementation of the National IDD Council program in 2001 among 7-10-year-old children in Semnan province.

In this cross sectional study, 1200 children, (M/F ratio=1), aged 7-10 years, were selected and grading of goiter was performed in accordance to the WHO criteria. Urinary samples were obtained from 120 children and urinary iodine was measured using digestion method.

Total prevalence of goiter was 17% (16.3% in girls and 17.7% in boys). The median urinary iodine was 13.7µg/dl. 73.2% had a urinary iodine of more than 10µg/dl, while 10.8% had urinary iodine levels of <5µg/dl. None of the candidates had urinary iodine levels less the 2µg/dl. There was no significant difference between the two sexes and urban or rural areas.

There has been a significant decline in the prevalence of goiter among children in Semnan province. In addition, urinary iodine concentration of children has reached rates approved by the WHO. Semnan province can now be classified as one of the "iodine-deficiency-free" areas in Iran.

Iodine deficiency disorder (IDD) is a worldwide health problem. Parts of Iran, such as Tehran, had been known as endemic areas for goiter. IDD was accepted as a priority health problem in our country and a National IDD Council was formed in 1989. This study was performed to evaluate the National IDD Council program in 2001 among 7-10-year-old children in Tehran province.

In this cross sectional study, 1200 children (M/F ratio=1), aged 7-10 years, were selected and grading of goiter was performed in accordance to the WHO criteria. Urinary samples were obtained from 120 children and urinary iodine was measured using digestion method.

Total prevalence of goiter was 5.1% (3.5% in girls and 6.3% in boys). The median urinary iodine was 19µg/dl. 80.8% had urinary iodine of more than 10µg/dl, while 11.2% had urinary iodine levels of <5µg/dl. None of the candidates has urinary iodine of less the 2µg/dl. There was no significant difference between sexes and urban or rural areas.

Results have revealed that the total prevalence of goiter has significantly decreased among children in Tehran province, meanwhile, urinary iodine concentration of children has reached to WHO approved rate. Thus, Tehran province could be classified among "iodine-deficiency-free" areas in Iran.