Thyroid and obesity: not a one-way interaction

AI-Assisted Ultrasound for the Early Diagnosis of Antibody-Negative Autoimmune Thyroiditis

The prevalence of antibody-negative chronic autoimmune thyroiditis (SN-CAT) is increasing. The early diagnosis of SN-CAT can effectively prevent its further development. Thyroid ultrasound can diagnose autoimmune thyroiditis and predict hypothyroidism. Primary hypothyroidism with a hypoechoic pattern suggested by thyroid ultrasound and negative thyroid serum antibodies is the main basis for the diagnosis of SN-CAT. However, for early SN-CAT, only hypoechoic thyroid changes and serological antibodies are currently available. This study explored how to achieve an accurate and early diagnosis of SN-CAT and prevent the development of SN-CAT combined with hypothyroidism. The diagnosis of a hypoechoic thyroid by artificial intelligence is expected to be a breakthrough in the accurate diagnosis of SN-CAT.

Subclinical hypothyroidism, outcomes and management guidelines: a narrative review and update of recent literature

Subclinical hypothyroidism (SCH) is diagnosed when serum thyroid stimulation hormone (thyrotropin; TSH) levels are above the reference range, accompanied by levels of free thyroxine within its reference range. The management of SCH remains a diagnostic and therapeutic challenge despite many years of research relating to its epidemiology, aetiology, effectiveness of treatment and safety. European Thyroid Association (ETA) guidelines for the management of SCH were published almost a decade ago. This narrative review summarizes the clinical literature relating to SCH and outcomes since the publication of these guidelines. Clinical evidence emerging during the previous decade generally supports the view that SCH is associated with adverse outcomes to an extent that is intermediate between euthyroidism and overt hypothyroidism although evidence that treatment with thyroid hormone replacement is beneficial is lacking. Accordingly, the rationale for the recommendations for intervention in the ETA guidelines based on the age of the patient, level of serum TSH, symptoms and comorbidities remains valid today.

MAFLD in Patients with Cushing's Disease Is Negatively Associated with Low Free Thyroxine Levels Rather than with Cortisol or TSH Levels

Purpose

This study aims to analyze the clinical characteristic of metabolic associated fatty liver disease (MAFLD) in patients with active Cushing's disease (CD) and determine associations of thyroid hormones with MAFLD.

Methods

Patients with active CD were included in this cross-sectional study. All subjects were assessed for hepatic steatosis by abdominal ultrasonography and thyroid functions. Demographic and clinical characteristic parameters were collected for correlation analysis and logistic analysis.

Results

290 individuals with active CD were included in Huashan hospital from January 2014 to February 2022. We found that the prevalence of CD with MAFLD was 33.79%. The MAFLD group had a lower level of FT4 and a higher level of FT3/FT4 but no difference in levels of cortisol, 24 h UFC, TSH, TT4, TT3, and FT3. Correlation analysis showed positive associations of TSH, TT4, TT3, FT3, and FT3/FT4 with BMI. In age-, BMI-, sex-, cortisol-, and 24 h UFC-adjusted analysis, FT4 was independently associated with MAFLD in patients with CD. This association remained similar even after adjusting for the presence of metabolic syndrome components.

Conclusion

Lower FT4 levels were associated with higher risk of MAFLD in patients with CD. FT4 may be used as a helpful indicator to predict MAFLD and provide novel ideas for the treatment of MAFLD in patients with CD in the future.

Seronegative autoimmune diseases: A challenging diagnosis

Autoimmune diseases (AID) are increasingly prevalent conditions which comprise more than 100 distinct clinical entities that are responsible for a great disease burden worldwide. The early recognition of these diseases is key for preventing their complications and for tailoring proper management. In most cases, autoantibodies, regardless of their potential pathogenetic role, can be detected in the serum of patients with AID, helping clinicians in making a definitive diagnosis and allowing screening strategies for early -and sometimes pre-clinical- diagnosis. Despite their undoubted crucial role, in a minority of cases, patients with AID may not show any autoantibody, a condition that is referred to as seronegative AID. Suboptimal accuracy of the available laboratory tests, antibody absorption, immunosuppressive therapy, immunodeficiencies, antigen exhaustion, and immunosenescence are the main possible determinants of seronegative AID. Indeed, in seronegative AID, the diagnosis is more challenging and must rely on clinical features and on other available tests, often including histopathological evaluation and radiological diagnostic tests. In this review, we critically dissect, in a narrative fashion, the possible causes of seronegativity, as well as the diagnostic and management implications, in several AID including autoimmune gastritis, celiac disease, autoimmune liver disease, rheumatoid arthritis, autoimmune encephalitis, myasthenia gravis, Sjögren's syndrome, antiphospholipid syndrome, and autoimmune thyroid diseases.

Redefinition of Successful Treatment of Patients With Hypothyroidism. Is TSH the Best Biomarker of Euthyroidism?

In recent years evidence has accumulated supporting a revised view of the nature of euthyroidism and the biomarkers of thyroid function. Within the normal range, variations in thyroid hormone levels are associated with variations in clinical parameters and outcomes. There are therefore no readily identified individually specific optimum levels of thyroid hormones for any individual. Levels around the middle of the normal population range may best reflect euthyroidism. These levels may have evolutionary advantages on the basis that adverse outcomes often increase with divergence from such levels, and physiological processes tend to minimise such inter-individual and intra-individual divergence. In populations of predominantly untreated individuals, levels of thyroid hormones and in particular levels of free thyroxine (FT4) correlate more often with clinical parameters than do levels of thyrotropin (TSH). Levels of thyroid hormones may therefore be regarded as the best available biomarkers of euthyroidism and dysthyroidism. It follows that 'subclinical hypothyroidism' (normal FT4/raised TSH levels), rather than being an accurate marker of peripheral tissue hypothyroidism is more a marker of decreased thyroid reserve and prognosis. The recent evidence suggests that treatment of hypothyroxinemia, regardless of the TSH level, and monitoring therapy using FT4 and/or triiodothyronine levels, depending on the replacement regime, may result in more successful treatment of hypothyroidism than relying on thyrotropin levels for patient selection and subsequent treatment monitoring. The equivalents of mid-range levels of thyroid hormones (especially FT4), adjusted by individual comorbidity concerns, may be rational general replacement targets. These implications of the new evidence may create opportunities for novel trials of thyroid replacement therapy.

The application of new concepts of the assessment of the thyroid state to pregnant women

Recently proposed concepts regarding the nature and assessment of the thyroid state have provided a model more consistent with empiric evidence. It now appears likely that there are no such entities as thyroid set points and individual euthyroidism. Rather than there being discrete thyroid states, peripheral organ parameters are associated with thyroid function in a continuous manner. Thyroid hormone levels and, in particular, levels of free thyroxine now appear to be superior to thyrotropin levels as indicators of the thyroid state. Complicating the assessment of the correlations of the thyroid state with pregnancy outcomes are the contribution of the placenta to maternal thyroid function, fetal thyroid development, the multiple potential pathways to any particular outcome, the likely presence of small critical periods of time, the differing genetics of fetal and maternal tissues, and the unreliability of thyroid hormone assays. Nevertheless, there is no apparent reason for there to be a change in pregnancy to the basic principles of thyroid hormone action. The relationships between mild abnormalities of the thyroid state and pregnancy outcomes and the value of treating such mild abnormalities remain uncertain and controversial. The evidence suggests that further investigation of these clinical questions might better be based on thyroid hormone, particularly free thyroxine, levels. In the investigation of borderline low thyroid states, the categories of subclinical hypothyroidism and isolated hypothyroxinemia might both be abandoned with attention being directed to low free thyroxine levels regardless of the thyroid-stimulating hormone (TSH) levels. For these changes to occur, there would ideally be improvements in the assays for free thyroxine in pregnancy. The evidence suggests that, just as in the non-pregnant situation, pregnancy guidelines based on thyrotropin levels may need revision.

Intensity Dependent Effects of Interval Resistance Training on Myokines and Cardiovascular Risk Factors in Males With Obesity

OBJECTIVE

To determine the effects of different intensities of interval resistance training (IRT) protocols on the levels of select myokines (decorin, follistatin, myostatin, activin A, transforming growth factor beta-1 [TGF-β1]), and cardiometabolic and anthropometric measures in males with obesity.

METHODS

Forty-four obese males (age: 27.5 ± 9.4 yr.; height: 165.4 ± 2.8 cm; weight: 97.9 ± 2.6 kg and BMI: 35.7 ± 4.3 kg/m²) were randomly assigned to one of four groups (n=11 per group): low-intensity interval resistance training (LIIRT), moderate-intensity interval resistance training (MIIRT), high-intensity interval resistance training (HIIRT) or control (C). The LIIRT group performed 10 exercises in 3 sets of 40% (20 repetitions), the MIIRT group performed 10 exercises in three sets of 60% (13 repetitions), and the HIIRT group performed 10 exercises in three sets of 80% (10 repetitions) of one maximum repetition (1RM), which were followed with active rest of 20% of 1RM and 15 repetitions. The resistance training groups exercised ~70 min per session, 3 days per week, for 12 weeks. Measurements were taken at baseline and after 12 weeks of exercise training.

RESULTS

Baseline levels of myokines, cardiovascular risk factors, anthropometry, body composition, and cardio-respiratory fitness were not different between the four groups (p>0.05). The group x time interactions for decorin, activin A, follistatin, myostatin, and TGF-β1, total cholesterol (TC), triglyceride (TG), high-density cholesterol (HDL), low-density cholesterol (LDL), anthropometry, body composition, and cardio-respiratory fitness were statistically significant (p<0.05). There were increases in post-test values for decorin, follistatin, HDL (p<0.05) and decreases in TC, TG, TGF-β1, LDL, and myostatin levels in the LIIRT, MIIRT, and HIIRT groups compared to pretest values (p<0.05). Changes in fat mass, VO_2peak, HDL, TG, glucose, activin A, decorin were not significant in LIIRT compared to the control group, while changes in activin A, follistatin, and TFG-β1 levels were greater in HIIRT and MIIRT groups compared to the LIIRT group (p<0.05).

CONCLUSION

The LIIRT, MIIRT, and HIIRT protocols all produced beneficial changes in decorin, activin A, follistatin, myostatin, and TGF-β1 levels, and cardiometabolic risk factors, with greater effects from the MIIRT and HIIRT protocols compared to LIIRT.

Inflammasome activation as a link between obesity and thyroid disorders: Implications for an integrated clinical management

Obesity is strongly associated with chronic low-grade inflammation. Obese patients have an increased risk to develop thyroid autoimmunity and to became hypothyroid, suggesting a pathogenetic link between obesity, inflammation and autoimmunity. Moreover, type 2 diabetes and dyslipidemia, also characterized by low-grade inflammation, were recently associated with more aggressive forms of Graves' ophthalmopathy. The association between obesity and autoimmune thyroid disorders may also go in the opposite direction, as treating autoimmune hyper and hypothyroidism can lead to weight gain. In addition, restoration of euthyroidism by L-T4 replacement therapy is more challenging in obese athyreotic patients, as it is difficult to maintain thyrotropin stimulation hormone (TSH) values within the normal range. Intriguingly, pro-inflammatory cytokines decrease in obese patients after bariatric surgery along with TSH levels. Moreover, the risk of thyroid cancer is increased in patients with thyroid autoimmune disorders, and is also related to the degree of obesity and inflammation. Molecular studies have shown a relationship between the low-grade inflammation of obesity and the activity of intracellular multiprotein complexes typical of immune cells (inflammasomes). We will now highlight some clinical implications of inflammasome activation in the relationship between obesity and thyroid disease.

Association of thyroid function, within the euthyroid range, with cardiovascular risk: The EPIPorto study

BACKGROUND

Thyroid hormones are important modulators of cardiovascular function. Both hypothyroidism and hyperthyroidism are known to contribute to an increased cardiovascular risk. It remains uncertain whether thyroid hormones level within the euthyroid range are associated with cardiometabolic risk. We aimed to evaluate the association between thyroid function levels within the euthyroid range and cardiovascular risk in a population-based cohort.

METHODS

Eight hundred thirty-five subjects aged ≥45 years from the EPIPorto population-based cohort were included. We excluded participants with TSH, free T4 (FT4), or free T3 (FT3) outside of the reference range, or with previous cardiovascular or thyroid disease. The associations between thyroid function, cardiovascular risk factors and the 10-year estimated risk of cardiovascular events (using SCORE2 and SCORE2-OP) were evaluated in linear and logistic regression models, crudely and adjusting for age, sex, BMI, diabetes, and smoking.

RESULTS

The mean age of the participants was 61.5 (SD 10.5) years and 38.9% were men. Eleven percent of the participants had diabetes, 47.8% had dyslipidemia, and 54.8% had hypertension. The mean body mass index (BMI) was 27.4 (SD 4.6) kg/m², and the median (percentile25-75) 10-year risk of cardiovascular events was 5.46% (2.92, 10.11). Participants with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. Lower FT3/FT4 ratio and higher FT4 levels were associated with higher prevalence of diabetes and more adverse lipid profile. Higher TSH, lower FT3 and lower FT3/FT4 ratio were associated with lower eGFR. Lower FT3, lower FT3/FT4 ratio and higher FT4 were associated with an increased 10-year risk of cardiovascular events.

CONCLUSIONS

In a population-based study, variations of thyroid function within the euthyroid range were associated with cardiovascular risk factors. On one hand, individuals with higher BMI, larger waist circumference and higher hs-CRP had higher levels of FT3 and FT3/FT4 ratio. On the other hand, a decreased conversion of T4 to T3 (lower FT3, lower FT3/FT4 ratio and/or higher FT4) was associated with a higher prevalence of diabetes, a more adverse lipid profile, a lower eGFR and an increased 10-year risk of cardiovascular events.

Basal and longitudinal changes in serum levels of TSH in morbid obese patients experiencing failure or success of dietary treatment

PURPOSE

The relationship between thyroid function and obesity is a widely investigated one. The impact of thyroid hormones in determining the outcome of dietary/lifestyle interventions remains to be fully elucidated. The aim of this study was to compare basal and post dietary-intervention circulating thyroid-function parameters, lipid profile and fasting-glucose in euthyroid obese patients according to a success or failure of a dietary intervention program.

METHODS

In a retrospective longitudinal case-control study we enrolled 50 euthyroid obese patients who experienced a success in dietary intervention, as defined by a BMI reduction of at least 5% from baseline (Success Group) and 50 sex and age-matched euthyroid obese patients who experienced failure in dietary intervention as defined by either stable or increased body weight throughout the follow-up (Failure Group). Serum thyroid function parameters and metabolic profile at baseline and at the end of follow-up were collected.

RESULTS

At baseline, the two groups showed similar BMI, total-cholesterol, HDL-cholesterol and fasting-blood-glucose, but patients in Success Group had a significantly higher TSH as compared with Failure Group (2.20 ± 0.97 vs 1.66 ± 0.73, respectively, p < 0.001). Throughout a mean follow-up of 21.4 months TSH significantly decreased in Success Group (2.20 ± 0.97 vs 2.06 ± 0.98; p = 0.029) and increased in Failure Group (1.63 ± 0.72 vs 2.01 ± 0.99; p < 0.001). Multiple regression analysis showed that the outcome of the dietary intervention was significantly and independently related to baseline BMI (0.925; 0.861-0.993), age (0.957; 0.922-0.993), TSH (0.531; 0.290-0.973) and TSH-changes (1.011; 1.000-1.022) during follow-up.

CONCLUSIONS

Baseline serum TSH level is related to the final outcome of a dietary intervention program in obese patients.

LEVEL OF EVIDENCE III

Evidence obtained from a retrospective cohort or case-control analytic studies.

Patterns of Bodyweight Changes in Patients With Hypothyroidism, a Retrospective Study From Basrah, Southern Iraq

Background

Weight gain is one of the most important hypothyroidism-related concerns in patients with hypothyroidism. However, unexpectedly, levothyroxine replacement does not necessarily result in body weight (BWT) reduction among those patients. The study aimed to assess the patterns of BWT changes through time in patients with hypothyroidism.

Method

In a retrospective database study from Faiha Specialized Diabetes, Endocrine, and Metabolism Center, a total of 346 adult patients with hypothyroidism (192 newly diagnosed and 154 known hypothyroidism patients) who had one visit every three months, five visits in one year were included. Of these, 116 new and 69 known hypothyroidism patients had completed nine visits in two years. Each visit involved thyroid-stimulating hormone (TSH) and BWT measurements. Patients with chronic liver or renal disease, diabetes mellitus, thyroid cancer, or other malignancies, pregnancy, and steroid or hormonal therapies were excluded. The patients were further subdivided based on average TSH levels into controlled (TSH ≤ 4.2 μIU/ml) and uncontrolled (TSH > 4.2 μIU/ml). Repeated measures analysis of variance (ANOVA) with a Greenhouse-Geisser correction and post hoc tests using the Bonferroni correction were used to evaluate TSH and BWT changes through the study.

Results

Both in newly diagnosed and known hypothyroidism patients with an average TSH > 4.2 μIU/mL, BWT increased significantly through visits over one and two years. For newly diagnosed patients assessed over one year (F(2.41, 321.60) = 3.28, p = 0.03), the mean BWT increase was 1.4 ± 0.38 kg from 3rd to 12th month visits (p = 0.004). For newly diagnosed patients assessed over two years (F(3.10, 263.89) = 9.08, P < 0.0005), the mean BWT increase was 3.02 ± 0.77 kg from 3rd to 24th month visits (p = 0.007). For patients with known hypothyroidism assessed over one year (F(2.56, 187.47) = 7.11, p = 0.0003), the mean BWT increase was 1.97 ± 0.64 kg at 12th month visit, and over two years (F(2.35, 77.56) = 4.67, P = 0.009), the mean BWT increase was 3.78 ± 1.26 kg at 24th month visit. While in all other patients with an average TSH ≤ 4.2 μIU/mL, the BWT changed non-significantly through the visits for newly diagnosed patients over one year and two years (p = 0.10, 0.34, respectively), and known patients over one year and two years (p = 0.47, 0.34, respectively).

Conclusion

Contrary to what is believed, adequate treatment with levothyroxine does not associate with weight reduction. Instead, either the patient kept on the same weight or continued to gain more weight.

Effect of the Cut-Off Level for Thyroid-Stimulating Hormone on the Prevalence of Subclinical Hypothyroidism among Infertile Mexican Women

The primary aim of this study was to compare the prevalence of subclinical hypothyroidism (SCH) using two different cut-off levels for TSH values (≥2.5 mIU/L versus ≥4.1 mIU/L). The secondary objective was to analyze the clinical-biochemical characteristics in women with and without SCH. This was a retrospective cross-sectional study. In total, 1496 Mexican women with infertility were included: Group 1, women with TSH levels ranging between 0.3 and 2.49 mIU/L, n = 886; Group 2, women with TSH between 2.5 and 4.09 mIU/L, n = 390; and Group 3, women with TSH ≥4.1 mIU/L n = 220. SCH prevalence was 40.7% (CI 95%: 38.3-43.3%) with TSH cut-off ≥ 2.5 mIU/L, and 14.7% (CI 95%: 12.7-16.5%) with TSH cut-off ≥ 4.1 mIU/L, (p = 0.0001). The prevalence of overweight was higher in Group 2 than in Groups 1 and 3. Thyroid autoimmunity, obesity and insulin resistance were higher in Group 3 than in Group 1 (p < 0.05). No other differences were observed between groups. Conclusions: The prevalence of SCH in our selected patients increased almost three times using a TSH cut-off ≥ 2.5 mIU/L compared with a TSH cut-off ≥ 4.1 mIU/L. Women with TSH ≥4.1 mIU/L compared with TSH cut-off ≤ 2.5 mIU/L more often presented with obesity, thyroid autoimmunity and insulin resistance.

Early Detection of Abnormal Growth Associated with Juvenile Acquired Hypothyroidism

CONTEXT

Development of the typical growth phenotype in juvenile acquired hypothyroidism (JHT), the faltering linear growth with increasing weight, has not been thoroughly characterized.

OBJECTIVE

To describe longitudinal growth pattern in children developing JHT and investigate how their growth differs from the general population in systematic growth monitoring.

DESIGN

Retrospective case-control study.

SETTING

JHT cases from 3 Finnish University Hospitals and healthy matched controls from primary health care.

PATIENTS

A total of 109 JHT patients aged 1.2 to 15.6 years (born 1983-2010) with 554 height and weight measurements obtained for 5 years preceding JHT diagnosis. Each patient was paired with 100 healthy controls (born 1983-2008) by sex and age. Longitudinal growth pattern was evaluated in mixed linear models. Growth monitoring parameters were evaluated using receiver operating characteristics analysis.

RESULTS

At diagnosis, JHT patients were heavier (mean adjusted body mass index-for-age [BMISDS] difference, 0.65 [95% CI, 0.46-0.84]) and shorter (mean adjusted height-for-age deviation from the target height [THDEVSDS] difference, -0.34 [95% CI, -0.57 to -0.10]) than healthy controls. However, 5 years before diagnosis, patients were heavier (mean BMISDS difference, 0.33 [95% CI, 0.12-0.54]) and taller (mean THDEVSDS difference, 0.29 [95% CI, 0.06-0.52]) than controls. JHT could be detected with good accuracy when several growth parameters were used simultaneously in screening (area under the curve, 0.83 [95% CI, 0.78-0.89]).

CONCLUSIONS

Abnormal growth pattern of patients with JHT evolves years before diagnosis. Systematic growth monitoring would detect abnormal growth at an early phase of JHT and facilitate timely diagnosis of JHT.

Clinical Parameters Are More Likely to Be Associated with Thyroid Hormone Levels than with Thyrotropin Levels: A Systematic Review and Meta-Analysis

Background: Though the functional states of other endocrine systems are not defined on the basis of levels of controlling hormones, the assessment of thyroid function is based on levels of the controlling hormone thyrotropin (TSH). We, therefore, addressed the question as to whether levels of thyroid hormones [free thyroxine (fT4), total triiodothyronine (TT3)/free triiodothyronine (fT3)], or TSH levels, within and beyond the reference ranges, provide the better guide to the range of clinical parameters associated with thyroid status. Methods: A PubMed/MEDLINE search of studies up to October 2019, examining associations of levels of thyroid hormones and TSH, taken simultaneously in the same individuals, with clinical parameters was performed. We analyzed atrial fibrillation, other cardiac parameters, osteoporosis and fracture, cancer, dementia, frailty, mortality, features of the metabolic syndrome, and pregnancy outcomes. Studies were assessed for quality by using a modified Newcastle-Ottawa score. Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were followed. A meta-analysis of the associations was performed to determine the relative likelihood of fT4, TT3/fT3, and TSH levels that are associated with the clinical parameters. Results: We identified 58 suitable articles and a total of 1880 associations. In general, clinical parameters were associated with thyroid hormone levels significantly more often than with TSH levels-the converse was not true for any of the clinical parameters. In the 1880 considered associations, fT4 levels were significantly associated with clinical parameters in 50% of analyses. The respective frequencies for TT3/fT3 and TSH levels were 53% and 23% (p < 0.0001 for both fT4 and TT3/fT3 vs. TSH). The fT4 and TT3/fT3 levels were comparably associated with clinical parameters (p = 0.71). More sophisticated statistical analyses, however, indicated that the associations with TT3/fT3 were not as robust as the associations with fT4. Conclusions: Thyroid hormones levels, and in particular fT4 levels, seem to have stronger associations with clinical parameters than do TSH levels. Associations of clinical parameters with TSH levels can be explained by the strong negative population correlation between thyroid hormones and TSH. Clinical and research components of thyroidology currently based on the measurement of the thyroid state by reference to TSH levels warrant reconsideration.

Compared with classic Hashimoto's thyroiditis, chronic autoimmune serum-negative thyroiditis requires a lower substitution dose of L-thyroxine to correct hypothyroidism

PURPOSE

Serum-negative-chronic-autoimmune-thyroiditis (SN-CAT) is considered a milder variant of classic Hashimoto's thyroiditis (CHT). However, its prevalence remains unknown and it is still unclear whether SN-CAT behaves differently in terms of L-thyroxine (LT4) substitution treatment of hypothyroidism. Aims of this study were to estimate the prevalence of SN-CAT in a large series of hypothyroid patients and to compare LT4 requirements in hypothyroid patients with SN-CAT and CHT.

METHODS

Five-hundred-eighty-one consecutive patients with primary-autoimmune-hypothyroidism were enrolled in a cross-sectional study. LT4 requirements and thyroid-volume changes were longitudinally evaluated in 49 hypothyroid patients with SN-CAT and in 98 sex and age-matched hypothyroid patients with CHT.

RESULTS

In our series the prevalence of SN-CAT was 20.8%. At diagnosis, patients in the CHT and SN-CAT groups had similar male/female ratio, age and BMI, while serum TSH and thyroid-volume were significantly greater in the CHT group. In the longitudinal study, during a follow-up of 8.9 ± 4.6 years, 8 out of 49 (16.3%) SN-CAT patients developed positive tests for of circulating TPO-Ab and/or Tg-Ab. Thyroid-volume significantly decreased in CHT patients, but not in those with SN-CAT. The maximum daily substitution dose of LT4 was smaller in SN-CAT patients as compared with the CHT ones. Multivariate analysis showed that age, BMI, basal TSH and thyroid antibody status independently and significantly predicted the maximum daily substitution dose of LT4.

CONCLUSIONS

SN-CAT accounts for a significant proportion of patients with autoimmune hypothyroidism. Compared with hypothyroid patients diagnosed with CHT, the SN-CAT ones require smaller doses of LT4 to correct their hypothyroidism.

Elevated serum TSH concentrations are associated with higher BMI Z-scores in southern Iranian children and adolescents

Background

Subclinical hypothyroidism is defined as elevated TSH levels while T4 or FT4 levels are normal. Elevated TSH levels are linked with obesity in adults. In a recent meta-analysis in Iran, 6.1% of children below 18 had obesity. Due to the low number of studies on the subject in children we, designed the study to assess the relation between BMI Z-score and TSH levels in children and adolescence.

Method

This cross-sectional study was performed in a pediatric endocrinology clinic in Shiraz. Children aged between 2 to 18 years that came to the clinic for routine growth assessment follow up from January till April 2018 were considered. 850 children including 365 boys and 485 girls were included.

Results

Prevalence of subclinical hypothyroidism is increased in higher BMI groups. 9.9, 13.8, 17.2 and 20.5% of underweight, healthy weight, overweight and obese had subclinical hypothyroidism respectively. Obese and overweight participants had higher odds of subclinical hypothyroidism than those who were not (OR:1.649, P = 0.010, CI95% 1.126–2.413). On the other hand, Subclinical hypothyroid participants had higher odds of overweight or obesity than those who were euthyroid (OR:1.650, P = 0.010, CI95% 1.128–2.413). When TSH is set as a dependent value, TSH level is increased (β = 0.126, r = 0.125, P = 0.001) with an increase in BMI Z-score. When BMI Z-score is set as a dependent value, BMI Z-score is increased (β = 0.113, r = 0.243, P = 0.001) with an increase in TSH level.

Conclusion

BMI Z-score and elevated TSH levels are positively correlated however studies should be performed on establishing the causality.

Preoperative Thyroid Autoimmune Status and Changes in Thyroid Function and Body Weight After Bariatric Surgery

BACKGROUND

Bariatric surgery has emerged as the most effective therapy for morbid obesity. There is increasing evidence that bariatric surgery could alleviate systemic inflammation and influence thyroid function. The current study aimed to investigate the associations of preoperative thyroid autoimmune status with the changes in body weight and thyroid function after bariatric surgery.

METHODS

We recruited 101 patients with morbid obesity (44 men and 57 women) who received bariatric surgery at Zhongshan Hospital, Fudan University. Those who had used thyroid hormone replacement or antithyroid drugs were excluded. General linear models were used to compare the changes in body weight and thyroid function in participants with different thyroid autoimmune statuses.

RESULTS

After bariatric surgery, serum-free triiodothyronine (FT3) (4.94 ± 0.73 vs 4.33 ± 0.59 pmol/L, P < 0.001) and thyroid-stimulating hormone (TSH) (3.13 ± 1.59 vs 2.26 ± 1.26 μIU/mL, P < 0.001) were significantly reduced, accompanied by reductions in BMI (42.1 ± 7.6 vs 31.4 ± 6.5 kg/m², P < 0.001), and estimated basal metabolic rate (2002 ± 398 vs 1700 ± 336 kcal/day, P = 0.001) and an improvement in lipid profiles. Serum thyroperoxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) levels also decreased significantly from 79.3 and 177.1 IU/mL to 57.8 and 66.0 IU/mL in participants with positive thyroid antibodies (P < 0.05). Further analysis showed that the positive preoperative thyroid autoimmune status was associated with less reduction in serum TSH (0.05 ± 1.59 vs - 1.00 ± 1.43 μIU/mL, P = 0.021) and BMI (- 8.3 ± 3.6 vs - 11.0 ± 4.5 kg, P = 0.049) after bariatric surgery.

CONCLUSION

Our study highlights a group of patients with morbid obesity, who have positive preoperative thyroid autoimmunity and less reduction in serum TSH levels and body weight after bariatric surgery.

The Association of Obesity with Autoimmune Thyroiditis and Thyroid Function-Possible Mechanisms of Bilateral Interaction

A growing number of patients suffer from autoimmune diseases, including autoimmune thyroid disease. There has simultaneously been a significant increase in the prevalence of obesity worldwide. It is still an open question whether adiposity can directly influence activation of inflammatory processes affecting the thyroid in genetically predisposed individuals. Adipokines, biologically active substances derived from the adipocytes, belong to a heterogenic group of compounds involved in numerous physiological functions, including the maintenance of metabolism, hormonal balance, and immune response. Notably, the presence of obesity worsens the course of selected autoimmune diseases and impairs response to treatment. Moreover, the excess of body fat may result in the progression of autoimmune diseases. Nutritional status, body weight, and energy expenditure may influence thyroid hormone secretion. Interestingly, thyroid hormones might influence the activity of adipose tissue as metabolic alterations related to fat tissue are observed under pathological conditions in which there are deficits or overproduction of thyroid hormones. Functioning TSH receptors are expressed on adipocytes. Thermogenesis may presumably be stimulated by TSH binding to its receptor on brown adipocytes. There could be a bilateral interaction between the thyroid and adipose. Obesity may influence the onset and course of autoimmune disease.

Impact of Abdominal Obesity on Thyroid Auto-Antibody Positivity: Abdominal Obesity Can Enhance the Risk of Thyroid Autoimmunity in Men

BACKGROUND

The interrelation between obesity and autoimmune thyroid diseases is complex and has not been confirmed. The aim of the present study was to observe the relationship between thyroid autoimmunity and obesity, especially abdominal obesity, in a large population.

METHODS

A total of 2253 residents who had lived in Xinjiang for more than 3 years were enrolled. Serum thyroid hormone concentration, thyroid autoantibodies, lipid parameters, Weight, height, and waist and hip circumference were measured.

RESULTS

The prevalence of thyroid peroxidase antibody (TPOAb) and/or thyroglobulin antibody (TgAb) positive was 32.1% (21.2% in men and 37% in women, P < 0.01). Compared with women, men had significantly higher TG levels, waist circumference, and hip circumference levels (P < 0.01), while women showed higher TSH, TPOAb, and TgAb levels (P < 0.01). The prevalence of overweight and obesity was 71.1% in men and 63.5% in women. Men had a higher prevalence of abdominal obesity than women (56.6% in men and 47.6% in women, P < 0.01). TPOAb correlates positively with waist circumference (r = 0.100, P < 0.05) in men. Binary logistic analysis showed that TPOAb positivity had increased risks of abdominal obesity in men, and the OR was 1.1044 (95% CI 1.035, 1.151, P < 0.05).

CONCLUSION

Our results indicate that men had higher lipid levels, thicker waist circumference, and higher prevalence of overweight, obesity, and abdominal obesity. Abdominal obesity is a risk factor for TPOAb positivity in men, suggesting that abdominal obesity can enhance the risk of thyroid autoimmunity in men.

The effect of concurrent aerobic-resistance training on thyroid hormones, blood glucose hemostasis, and blood lipid indices in overweight girls with hypothyroidism

Background

The present study aimed to explore the effect of 8 weeks of concurrent aerobic-resistance training on thyroid stimulating hormone (TSH), thyroxine (T4), blood lipid profile, and blood glucose hemostasis in adolescent girls with hypothyroidism.

Materials and methods

In this clinical trial, 20 adolescent girls with hypothyroidism [age: 12.10 ± 1.94 years; body mass index (BMI): 25.25 ± 2.91 kg/m2] were selected and randomly assigned to experimental and control groups. The experimental group was treated with 8 weeks of concurrent aerobic [60–80% heart rate reserve (HHR)] and resistance (40–65% of 1RM) training. Blood was sampled before and after training. Data were analyzed using a pairwise t-test and an independent t-test (α < 0.05).

Results

Within-group comparison revealed significant decline of body index, BMI, fat percentage, fasting blood sugar, and homeostatic model assessment (HOMA) in the experimental group (p = 0.002, p = 0.001, p = 0.001, p = 0.03, and p = 0.02, respectively). Also, inter-group comparisons indicated significant differences in weight, BMI, fat percentage and HOMA (p = 0.001). But, no significant difference was observed in the blood sugar index (p > 0.05).

Conclusion

A short-term period of concurrent aerobic-resistance training may improve blood glucose hemostasis and body composition of adolescent girls with hypothyroidism. However, further research is necessary.

Thyroid function before and after Roux-en-Y gastric bypass: an observational study

BACKGROUND

Population studies have shown a positive association between thyroid-stimulating hormone (TSH) and body mass index. Recent studies have shown a significant increase in the prevalence of subclinical hypothyroidism (SCH) in obesity. Weight reduction after Roux-en-Y gastric bypass (RYGB) seems to significantly decrease TSH levels.

OBJECTIVES

The purpose of this study was to evaluate the prevalence of SCH in obese patients (class II and III) and to observe the behavior of thyroid hormones (TSH, hormone triiodothyronine, thyroxine, free thyroxine) with significant weight loss after RYGB.

SETTING

Hospital Nossa Senhora das Graças, Curitiba, Paraná, Brazil.

METHODS

We retrospectively reviewed the medical records of 215 obese patients who underwent RYGB between 2005 and 2012 with a follow-up of at least 2 years. The study was observational and descriptive. The selected times for clinical and laboratory evaluations were preoperative, 3, 6, 12, and 24 months after the procedure. Association, correlation, and variance analyses were performed.

RESULTS

The prevalence of SCH preoperatively was 9.3%. SCH was corrected in 89.5% of patients 12 months after RYGB. We did not find an association between TSH and BMI (r = .002, P = .971). There was a positive impact of bariatric surgery on all metabolic variables. We showed that serum TSH level had no positive correlation with the presence or absence of metabolic syndrome.

CONCLUSIONS

Weight loss after bariatric surgery leads to normalization of TSH levels in most patients and none developed overt hypothyroidism. Obese patients with SCH should not be treated with thyroid hormone replacement. Serial monitoring of thyroid function after obesity therapy seems to be a reasonable approach.

Screening for Thyroid Dysfunction in Pregnancy With Targeted High-Risk Case Finding: Can It Be Improved?

CONTEXT AND OBJECTIVE

Targeted screening is proposed for the detection of thyroid dysfunction in pregnant women rather than universal screening (US). We aimed to determine the detection rate of subclinical hypothyroidism (SCH) and overt hypothyroidism (OH) based on American Thyroid Association guidelines (ATA-GL) and whether it could be improved.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study of 1832 pregnant women in a single center. Thyroid function (TSH and free T4) and iron status were determined. The high-risk group (HRG) included women with one or more ATA-GL risk factors and the low-risk group (LRG) included women without. Participants with other risk factors [body mass index (BMI) 30 to 39.9 kg/m2, Caucasian background] were classified as HRG+ and those with iron deficiency as HRG++.

RESULTS

The HRG included 64% of women and the LRG included 36% (P < 0.001). Of all participants, 4.5% had SCH and 0.5% OH. The detection rate of SCH and OH was comparable between the LRG and HRG (46% vs 54% and 25% vs 75%; P = 0.560 and 0.157, respectively). In the HRG, the detection rate of SCH was lower than that of US (54% vs 100%; P < 0.001), but that of OH was comparable (75%; P = 0.596). The detection rate of SCH in the HRG+ and HRG++ was comparable to that in the US group (81% and 88% vs 100%; P = 0.220 and 0.439, respectively).

CONCLUSIONS

Targeted high-risk case finding screening was not effective for the detection of SCH but performed better for OH. When obesity in the range BMI 30 to 39.9 kg/m2 and a Caucasian background were included as risk factors, the detection rate of SCH became comparable with that of US.

Prevalence of newly established thyroid disorders in patients with moderate-to-severe obstructive sleep apnea syndrome

BACKGROUND

Hypothyroidism can directly cause obstructive sleep apnea (OSA) but may also contribute to it through its impact on the metabolic syndrome. The purpose of this study was to establish the prevalence of known and newly diagnosed overt and subclinical hypothyroidism (SCH) among patients with OSA.

METHODS

We prospectively included all consecutive moderate or severe OSA patients referred for CPAP therapy. A fasting blood sample was collected to determine thyroid-stimulating hormone (TSH) and free T4 (FT4) levels.

RESULTS

A total of 280 patients were included (70% male). Mean ± SD body mass index (BMI) and apnea-hypopnea index (AHI) were 33 ± 7 kg/m² and 49 ± 25, respectively. Median (range) serum TSH levels and mean ± SD FT4 levels were comparable between severe and moderate OSA (1.7 (1.3-2.6) vs 2.1 (1.2-2.8); p = 0.378 and 15.3 ± 2.3 vs 15.3 ± 2.3; p = 0.981). TSH and FT4 levels were not correlated with AHI (p = 0.297 and p = 0.370, respectively), but TSH was correlated with BMI (p = 0.049).Of all patients, 8.9% had increased serum TSH levels (severe and moderate OSA patients had similar levels (p = 0.711)) and 8.2% were newly diagnosed patients (no differences were observed between severe and moderate OSA (p = 0.450)). A total of 16.4% of patients had some type of thyroid disorder. Thyroid function parameters were associated with BMI but not with the severity of OSA.

CONCLUSION

In our population of moderate or severe OSA, 16% of patients had a thyroid problem and 8% of these were newly diagnosed with SCH.

Subclinical Hypothyroidism among local adult obese population

OBJECTIVE

To determine the frequency of subclinical hypothyroidism in local adult obese population.

METHODS

The study was conducted at Hayatabad Medical Complex, Peshawar, from March, 2017 to August, 2017. All patients aged between 18 and 60 years with BMI of more than 29kg/m2 were included in the study. Patients on lipid lowering drugs, with renal failure, hepatic failure and already diagnosed cases of thyroid dysfunction were excluded from the study. Thyroid functions were measured for all patients.

RESULTS

A total of 127 adults were included in the study in a consecutive manner. Mean age was 34.5 + 7.9 years of which 46.5% were male and 53.5% were female. Mean BMI was 32.05±2.06 kg/m2. The mean serum TSH was 3.13±1.10 mIU/L and mean serum thyroxine level was 1.08±0.25ng/dl. Subclinical hypothyroidism was recorded in 15% of the study population.

CONCLUSION

Subclinical hypothyroidism is highly prevalent in our population with BMI of more than 29kg/m2. Further studies are recommended on relationship between thyroid functions and BMI and its effect on cardiovascular functions.

Variables Contributing to Thyroid (Dys)Function in Pregnant Women: More than Thyroid Antibodies?

Variability in thyroid function in pregnant women is the result of 2 main determinants, each accounting for approximately half of it. The first is the genetically determined part of which the knowledge increases fast, but most remains to be discovered. The second determinant is caused by an ensemble of variables of which thyroid autoimmunity is the best known, but also by others such as parity, smoking, age, and BMI. More recently, new candidate variables have been proposed, such as iron, endocrine disruptors, and the ethnicity of the pregnant women. In the future, the diagnosis and treatment of thyroid (dys)function may be optimized by the use of each individual's pituitary-thyroid set point, corrected with a factor taking into account the impact of nongenetically determined variables.

Thyroid-Stimulating Hormone, Degree of Obesity, and Metabolic Risk Markers in a Cohort of Swedish Children with Obesity

BACKGROUND/AIMS

Thyroid-stimulating hormone (TSH) is affected in obesity and might influence metabolic risk. It is unclear what mechanisms cause elevated TSH in obesity. We aimed to investigate TSH status within the normal range and the association of TSH with degree of obesity and metabolic parameters in children with obesity.

METHODS

A total of 3,459 children, aged 3.0-17.9 years, were identified in the Swedish Childhood Obesity Treatment Registry, BORIS. Age, gender, TSH, free triiodothyronine (fT3), free thyroxine (fT4), body mass index standard deviation scores (BMI SDS), as well as variables of lipid and glucose metabolism were examined.

RESULTS

Children with high-normal TSH (>3.0 mU/L) (28.8%) had higher BMI SDS compared to children with low-normal TSH (<3.0 mU/L) (p < 0.001). Multivariable regression analysis adjusted for age and gender showed that TSH levels were associated with BMI SDS (β: 0.21, 95% CI: 0.14-0.28, p < 0.001). Associations of thyroid hormones with markers of lipid and glucose metabolism were observed, where TSH was associated with fasting insulin, HOMA (homeostatic model assessment of insulin resistance), total cholesterol, and triglycerides.

CONCLUSIONS

A positive association between TSH levels and BMI SDS was seen in children with obesity. Associations of TSH and free thyroid hormones with glucose metabolism indicated that TSH might be one of several factors acting to determine body weight and obesity co-morbidities, although the underlying mechanism remains unclear.

Homeostatic Model Assessment-Insulin Resistance (HOMA-IR 2) in Mild Subclinical Hypothyroid Subjects

Despite various studies with conflicting results, the effect of thyroid hormones on lipids and insulin levels in dysthyroidism is of great interest. This case control study was aimed to perceive the existence of IR and dyslipidemia in mild subclinical hypothyroid subjects (TSH ≤ 9.9 µIU/ml) as compared to their age and gender matched euthyroid controls. Basic demographic information like height, weight was recorded. Serum samples of all the subjects were assayed for thyroid profile, lipid profile, blood glucose, HbA1C and insulin. BMI and insulin resistance was calculated. Compared to controls patients with mild subclinical hypothyroidism demonstrated hyperinsulinemia and dyslipidemia observed by the higher LDL cholesterol. A significantly positive correlation was observed for HOMA-IR with TSH and LDL cholesterol. Hence, even in the mild subclinical hypothyroid state assessment of thyroid function should be combined with estimation of plasma glucose, insulin and serum lipids to monitor and prevent its associated effects.

Pregnancy outcomes are not altered by variation in thyroid function within the normal range in women free of thyroid disease

OBJECTIVE

In the recently revised guidelines on the management of thyroid dysfunction during pregnancy, treatment with thyroid hormone (LT4) is not recommended in women without thyroid autoimmunity (TAI) and TSH levels in the range 2.5-4.0 mIU/L, and in a recent study in that particular group of pregnant women, more complications were observed when a treatment with LT4 was given. The objective of the study was therefore to investigate whether variation in thyroid function within the normal (non-pregnant) range in women free of thyroid disease was associated with altered pregnancy outcomes?

DESIGN

Cross-sectional data analysis of 1321 pregnant women nested within an ongoing prospective collection of pregnant women's data in a single centre in Brussels, Belgium.

METHODS

Thyroid peroxidase antibodies (TPO-abs), thyroid-stimulating hormone (TSH), free T4 (FT4) and ferritin levels were measured and baseline characteristics were recorded. Women taking LT4, with TAI and thyroid function outside the normal non-pregnant range were excluded. Pregnancy outcomes and baseline characteristics were correlated with all TSH and FT4 levels within the normal range and compared between two groups (TSH cut-off < and ≥2.5 mIU/L).

RESULTS

Tobacco use was associated with higher serum TSH levels (OR: 1.38; CI 95%: 1.08-1.74); P = 0.009. FT4 levels were inversely correlated with age and BMI (rho = -0.096 and -0.089; P < 0.001 and 0.001 respectively) and positively correlated with ferritin levels (rho = 0.097; P < 0.001). Postpartum haemorrhage (>500 mL) was inversely associated with serum FT4 levels (OR: 0.35; CI 95%: 0.13-0.96); P = 0.040. Also 10% of women free of thyroid disease had serum TSH levels ≥2.5 mIU/L.

CONCLUSIONS

Variation in thyroid function during the first trimester within the normal (non-pregnant) range in women free of thyroid disease was not associated with altered pregnancy outcomes. These results add evidence to the recommendation against LT4 treatment in pregnant women with high normal TSH levels and without TPO antibodies.

The Association of Triiodothyronine-to-Thyroxine Ratio with Body Mass Index in Obese Nigerian Children and Adolescents

The interest in the relationship between thyroid dysfunction and obesity is on the increase. This study compares the triiodothyronine-to-thyroxine (T3/T4) ratio in obese and lean children and adolescents, and correlates thyroid hormones with body mass index (BMI) in obese Nigerian children. It is a retrospective study of records of 76 obese children and adolescents with a BMI of 31.7 ± 0.1 kg/m² (26 males aged 10.9 ± 0.35 years, and 50 females aged 10.8 ± 0.4 years) that were referred to the laboratory for thyroid hormone evaluation because of their obese status. The controls were 20 age-matched non-obese apparently healthy subjects, with a mean age of 11.0 ± 0.47 years and a BMI of 20.2 ± 0.2 kg/m². Serum T3, T4, and thyroid stimulating hormone (TSH) were determined using ELECSYS 1010 auto-analyzer (Roche Diagnostics, Penzberg, Germany). The BMI (p < 0.001), T3 (p < 0.01), TSH (p < 0.001) and T3/T4 ratio (p < 0.001) were significantly higher in obese than non-obese children and adolescents. Triiodothyronine (r = 0.230; p < 0.05), TSH (r = 0.272; p < 0.02), and T3/T4 ratio (r = 0.232; p < 0.05) correlated positively with BMI in obese children and adolescents. The T3/T4 ratio (p < 0.005) was significantly higher in obese boys than obese girls. Serum T3, TSH, and T3/T4 ratio correlated positive with BMI in obese Nigerian children and adolescents. Since thyroid dysfunction represents a continuum from asymptomatic to clinical symptomatic disease, it is suggested that obese children be counseled on the need to maintain ideal BMI in order to avoid the risks associated with obesity.

Latent Hypothyroidism in Adults

BACKGROUND

The prevalence of latent/subclinical hypothyroidism is between 3% and 10%, according to epidemiologic studies that have been carried out in the USA, the United Kingdom, and Denmark. As persons with latent hypo - thyroidism are often asymptomatic, the diagnosis is often made incidentally in routine laboratory testing.

METHODS

This review is based on a selective search in PubMed for publications on the diagnosis and treatment of latent hypothyroidism. All pertinent articles and guidelines published from 1 January 2000 to 31 July 2016 were included.

RESULTS

The diagnosis of latent hypothyroidism is generally assigned after repeated measurement of a TSH concentration above 4.0 mU/L in a person whose fT4 concentration is in the normal range. The most common cause is autoimmune thyroiditis, which can be detected by a test for autoantibodies. L-thyroxin supplementation is a controversial matter: its purpose is to prevent the development of overt hypothyroidism, but there is a danger of overtreatment, which increases the risk of fracture. To date, no benefit of L-thyroxin supplementation has been demonstrated with respect to morbidity and mortality, health-related quality of life, mental health, cognitive function, or reduction of overweight. There is, however, evidence of a beneficial effect on cardiac function in women, and on the vascular system. At present, treatment is generally considered indicated only if the TSH level exceeds 10.0 mU/L.

CONCLUSION

Limited data are available on the relevant clinical endpoints and undesired side effects of supplementation therapy. Physicians should advise patients about the indications for such treatment on an individual basis after due consideration of the risks and benefits.

Maternal thyroid parameters in pregnant women with different ethnic backgrounds: Do ethnicity-specific reference ranges improve the diagnosis of subclinical hypothyroidism?

OBJECTIVE

Guidelines on the management of thyroid dysfunction during pregnancy have recently been updated and, for the diagnosis of subclinical hypothyroidism (SCH), a thyroid-stimulating hormone (TSH) upper reference limit (cut-off) of 4.0 mIU/L has been proposed when no institutional values are available. It is also suggested that serum TSH and thyroid autoimmunity (TAI) may be different according to the ethnic background of the women. We therefore determined the prevalence of TAI and SCH in pregnant women with different ethnic backgrounds and, to define SCH, we used different first trimester TSH upper reference cut-offs (institutional, ethnicity-specific, 2.5 mIU/L [Endocrine Society] and 4.0 mIU/L [American Thyroid Association]).

DESIGN

Cross-sectional data analysis of 1683 pregnant women nested within an ongoing prospective database of pregnant women.

METHOD

The study was performed in a single centre in Brussels, Belgium. During the first antenatal visit, thyroid peroxidase antibodies (TPO-abs), TSH and free T4 (FT4) were measured and baseline characteristics recorded. Data from 481 women with sub-Saharan (SaBg; 28.6%), 754 North African (NaBg; 44.8%) and 448 Caucasian (CaBg; 26.6%) backgrounds were analysed. For the calculation of TSH reference ranges, women with TAI, outliers, twin and assisted pregnancies were excluded.

RESULTS

The prevalence of TAI was significantly lower in the SaBg group than in NaBg and CaBg groups (3.3% vs 8.6% and 11.1%; P<.001, respectively). Median TSH was significantly lower in SaBg and NaBg groups as compared with the CaBg group (1.3 and 1.4 vs 1.5 mIU/L; P=.006 and .014, respectively). The prevalence of women with SCH was comparable between all groups when 2.5 mIU/L was used as cut-off, but when 4.0 mIU/L or the institutional cut-off (3.74 mIU/L) was used, it was significantly higher in the CaBg group vs the NaBg group (5.4% vs 2.1% and 7.1% vs 3.3%, P=.008 and .013, respectively). The use of ethnicity-specific cut-offs did not change the prevalence of SCH as compared to the use of institutional cut-offs. However, when these cut-offs were used, the prevalence of SCH reduced by >70% (4.5% instead of 16.7%; P<.001) relative to the 2.5 mIU/L cut-off.

CONCLUSIONS

Pregnant women with a sub-Saharan African background had a lower prevalence of TAI and TSH levels as compared with women from other backgrounds. The use of ethnicity-specific TSH cut-offs in early pregnancy was not more specific for the diagnosis of SCH as compared to the use of the institutional cut-off.

Impact of Obesity on Serum Levels of Thyroid Hormones among Euthyroid Saudi Adults

AIM OF STUDY

To assess serum thyroid hormones levels among Saudi adults and to correlate participants' serum levels with their grades of body mass index (BMI).

METHODOLOGY

A total of 278 adult subjects were recruited. Participants were categorized according to their BMI grades into normal weight (BMI < 25 kg/m2), overweight (BMI 25-29.9 kg/m2), or obese (BMI ≥ 30 kg/m2). Serum thyroid hormones levels were assessed at the central laboratory of Aseer Central Hospital, Abha City, by chemiluminescence immunoassay.

RESULTS

More than three-fourths of participants were either overweight (31.3%) or obese (44.6%). Mean TSH serum levels showed a significantly increasing trend with increasing BMI (p < 0.001). A negative trend was observed regarding participants' mean serum levels of fT4 with their BMI, but there were no significant differences in mean serum fT4 levels according to BMI. Moreover, no significant differences were observed in serum fT3 levels according to BMI.

CONCLUSIONS

Mean TSH serum levels increase with BMI increase. Further largescale multicentric and longitudinal studies are necessary to prove the association between serum levels of thyroid hormones and BMI of euthyroid adults.

Prevalence and Correlation of Hypothyroidism With Pregnancy Outcomes Among Lebanese Women

Purpose:

Assessment of hypothyroidism prevalence and clinical significance among pregnant women in Lebanon.

Methods:

We performed a single-center retrospective cohort study at the American University of Beirut Medical Center. Clinical, demographic, and laboratory data were collected and analyzed using trimester-specific ranges for hypothyroidism.

Results:

Of 920 pregnant women, 17% had hypothyroidism during gestation. A history of previous miscarriage and morbid obesity were associated with hypothyroidism during pregnancy. Pregnant women with hypothyroidism were more likely to experience a miscarriage during the first trimester [odds ratio, 2.9; 95% confidence interval, (1.13 to 7.5); P = 0.02] and delivery at post-term (odds ratio, 3.9; 95% confidence interval, 1.05 to 14.9; P = 0.05). We found no substantial correlation with preterm or premature delivery, cesarean section delivery, or gestational hypertension despite increased odds among the hypothyroidism group. No substantial differences were found with respect to the fetal outcomes between the control and hypothyroidism groups.

Conclusions:

Hypothyroidism is prevalent in 17% of pregnant women in Lebanon and was associated with a history of miscarriage and morbid obesity. The presence of hypothyroidism correlated with miscarriage during the first trimester and with post-term delivery. Despite the lack of sufficient data supporting the efficacy of treatment of hypothyroidism during gestation, more studies should be conducted to assess the effect of hypothyroidism on gestational and fetal outcomes.

Serum Thyroid Stimulating Hormone Levels Are Associated with the Presence of Coronary Atherosclerosis in Healthy Postmenopausal Women

Objectives

Menopause is a natural aging process causing estrogen deficiency, accelerating atherogenic processes including dyslipidemia. Prevalence of thyroid dysfunction is also high in postmenopausal women, and it is known to elevate the risk of cardiovascular disease (CVD). Therefore, we are to study on the associations in between serum thyroid stimulating hormone (TSH) and prevalence of CVD in postmenopausal women who have normal thyroid function.

Methods

We performed a retrospective review of 247 Korean postmenopausal women who visited the health promotion center from January, 2007 to December, 2009. Postmenopausal women with normal serum TSH were included in the study. Coronary atherosclerosis was assessed by 64-row multidetector computed tomography.

Results

In multiple linear regression analysis, serum TSH was associated with serum triglyceride (TG) (β = 0.146, P = 0.023). In multiple logistic regression analysis, increasing age and serum TSH were associated with an increased risk of coronary atherosclerosis in euthyroid postmenopausal women (odds ratio [OR] = 1.107 [1.024-1.197], P = 0.011 and OR = 1.303 [1.024-1.658], P = 0.031, respectively).

Conclusions

It revealed that significant predictor of serum TSH was serum TG, and increasing age and TSH were found to have associations with an increased risk of coronary atherosclerosis in euthyroid postmenopausal women. Screening and assessing risks for CVD in healthy postmenopausal women would be helpful before atherosclerosis develops.

Reference Intervals of Thyroid Function During Pregnancy: Self-Sequential Longitudinal Study Versus Cross-Sectional Study

BACKGROUND

A self-sequential longitudinal reference interval may be expected to minimize the inter-individual variation of thyroid function. Comparison between the self-sequential longitudinal reference interval (SLRI) and cross-sectional reference interval (CSRI) in pregnancy has not been well investigated. The objectives of this study were to establish a stringent SLRI of thyroid function in pregnant women and to compare it with the conventional CSRI.

METHODS

Three cohorts were enrolled: group 1, pregnant women for an SLRI (n = 99); group 2, pregnant women for a CSRI (n = 1318); group 3, non-pregnant control women (NC) as a control group (n = 301) according to the criteria of the National Academy of Clinical Biochemistry. Thyrotropin (TSH), total thyroxine (TT4), free thyroxine (fT4), total triiodothyronine (TT3), free triiodothyronine (fT3), serum ferritin (SF), and urine iodine concentration (UIC) were measured in the three groups.

RESULTS

Compared with CSRI, the reference interval of the SLRI group had narrower reference intervals of fT4 in the first and second trimesters (p < 0.05). The median of TSH was at a low level during the first trimester, and then gradually elevated in the second and third trimesters. The median of fT4 persistently decreased from 12 weeks, and did not return to the level of the NC group until 12 months postpartum. The TT4 increased to 131.4 nmol/L at gestational week 8, and reached a peak (170.0 nmol/L) at gestational week 12. In the first trimester, the prevalence of hypothyroxinemia was 9.1%, 4.0%, and 2.0% with a fT4 value below the 10th, 5th, and 2.5th percentile, respectively. In contrast, 29.3% of TT4 values were below the lower non-pregnancy reference limit multiplied by 1.5.

CONCLUSIONS

No significant difference was found between a SLRI and a CSRI, even in a stringent self-sequential longitudinal reference interval of thyroid function in pregnant women. In addition, the limit of TT4 below the non-pregnant level multiplied by a factor 1.5 is not appropriate for diagnosing hypothyroxinemia in the first trimester.

Obesity Does Not Modify the Risk of Differentiated Thyroid Cancer in a Cytological Series of Thyroid Nodules

BACKGROUND

A possible impact of obesity on the risk of thyroid cancer has been postulated in some studies, but it remains controversial.

OBJECTIVE

To investigate the association between obesity and differentiated thyroid carcinoma in a population of unselected patients subjected to fine-needle aspiration cytology (FNAC) for thyroid nodules.

METHODS

We retrospectively evaluated the results of FNAC of thyroid nodules in 4,849 patients (3,809 females and 1,040 males; mean age 55.9 ± 14.1 years). Patients were stratified according to their body mass index (BMI). There were 1,876 (38.7%) normal-weight patients (BMI 18-24.9), 1,758 (36.2%) overweight (BMI 25-29.9), 662 (13.7%) grade 1 obese (BMI 30-34.9), 310 (6.4%) grade 2 obese (BMI 35-39.9) and 243 (5.0%) grade 3 obese (BMI >40).

RESULTS

The prevalence of suspicious or malignant nodules (Thy4/Thy5) did not differ across the 5 BMI groups, i.e. it was 6.8% in normal-weight patients, 6.3% in overweight patients, 6.3% in grade 1 obese patients, 4.0% in grade 2 obese patients and 4.2% in grade 3 obese patients (p = 0.29). The prevalence of Thy4/Thy5 nodules did not differ when males and females were evaluated separately (p = 0.22 and p = 0.12, respectively). A significant, lower rate of Thy4/5 cytology was observed in female patients with grade 2-3 obesity (odds ratio 0.51; 95% confidence interval 0.284-0.920; p = 0.009).

CONCLUSIONS

The results of this study, in a retrospective series of patients with thyroid nodules, do not confirm previous findings reporting an association between obesity and differentiated thyroid carcinoma. Thus, obese patients with nodular thyroid disease should be managed the same as normal-weight patients.

Thyroid Function and Thyroid Autoimmunity in Relation to Weight Status and Cardiovascular Risk Factors in Children and Adolescents: A Population-Based Study

OBJECTIVE

In obese subjects, slight increases have been observed in thyrotropin [thyroid-stimulating hormone (TSH)] levels, but data in children are scarce. The aim of this study was to evaluate whether thyroid function and autoimmunity vary with weight status in a healthy population of children and adolescents and to determine whether hyperthyrotropinemia is associated with any cardiovascular risk factor.

METHODS

This cross-sectional epidemiological study was conducted in Almería (Spain) on a representative sample of 1317 healthy subjects aged 2-16 years. Thyroid function, thyroid autoimmunity and cardiovascular risk factors were measured. Chi-square test, analysis of variance and multiple linear regression were used in the statistical analyses.

RESULTS

The obese children and adolescents had thyrotropin levels (mean ± standard deviation) of 3.12±2.44 mU/L. These levels were higher than those of overweight subjects (2.79±1.51 mU/L) and of normal weight subjects (2.73±1.30 mU/L) (p=0.02). Levels of free thyroxine and urinary iodine did not differ significantly between the groups. The prevalence (95% confidence interval) of thyroid autoimmunity was lower in the individuals with normal weight (2.9%; 2.0-4.2) than in the overweight (6.3%; 3.9-9.9) and obese subjects (5.6%, 2.5-11.3) (p=0.02). TSH levels were associated with obesity (β=0.36; p<0.001) and thyroid autoimmunity (β=1.10; p<0.001). They were not associated with any cardiovascular risk factor.

CONCLUSION

Obese children and adolescents had higher levels of thyrotropin than those who were overweight and of normal weight. The differences among the groups were of very little clinical significance and could possibly be linked to the higher prevalence of thyroid autoimmunity in obese subjects. The hyperthyrotropinemia in these subjects was not associated with any cardiovascular risk factor.

Triagem de hipotireoidismo em crianças - Visão dos médicos da atenção primária à saúde de um município de médio porte

Objetivo: Avaliar quais parâmetros os médicos da atenção primária à saúde do município de São Carlos, SP, Brasil, adotam para realizar triagem de função tireoidiana em crianças e adolescentes, quais exames complementares são solicitados e qual a conduta diante de resultados laboratoriais alterados. Métodos: Estudo transversal descritivo, no qual participaram 26 profissionais, correspondendo a 96,3% de todos os médicos da atenção primária da cidade que atuam no cuidado de crianças e adolescentes. Os participantes responderam por escrito quais as três situações mais frequentes na prática clínica em que indicavam triagem de hipotireoidismo na população pediátrica, quais os exames laboratoriais solicitados nesta avaliação e a qual conduta frente a exames com resultados alterados. Resultados: As situações clínicas mais frequentes apontadas pelos participantes como indicações de avaliação tireoidiana foram: obesidade, com 23 respostas (88,5%); baixa estatura, com 16 (61,5%); e síndrome de Down, com 8 (30,8%). Nove médicos (34,6%) responderam realizar o rastreio pela dosagem de TSH e T4l e outros 9 (34,6%), pela dosagem de TSH isolado. A conduta mais frequente diante de um resultado alterado foi o encaminhamento ao endocrinologista pediátrico, com 14 respostas (53,8%). Conclusão: O cenário encontrado neste estudo mostra que exames de função tireoidiana são solicitados rotineiramente por médicos da atenção primária no acompanhamento de crianças obesas. Como a obesidade infantil tem uma alta prevalência, isso pode determinar aumento importante dos custos do serviço de saúde e sobrecarga nos serviços de atenção especializada.

Weight loss predictability by plasma metabolic signatures in adults with obesity and morbid obesity of the DiOGenes study

OBJECTIVE

Aim is to predict successful weight loss by metabolic signatures at baseline and to identify which differences in metabolic status may underlie variations in weight loss success.

METHODS

In DiOGenes, a randomized, controlled trial, weight loss was induced using a low-calorie diet (800 kcal) for 8 weeks. Men (N = 236) and women (N = 431) as well as groups with overweight/obesity and morbid obesity were studied separately. The relation between the metabolic status before weight loss and weight loss was assessed by stepwise regression on multiple data sets, including anthropometric parameters, NMR-based plasma metabolites, and LC-MS-based plasma lipid species.

RESULTS

Maximally, 57% of the variation in weight loss success can be predicted by baseline parameters. The most powerful predictive models were obtained in subjects with morbid obesity. In these models, the metabolites most predictive for weight loss were acetoacetate, triacylglycerols, phosphatidylcholines, specific amino acids, and creatine and creatinine. This metabolic profile suggests that high energy metabolism activity results in higher amounts of weight loss.

CONCLUSIONS

Possible predictive (pre-diet) markers were found for amount of weight loss for specific subgroups.

Indices of adiposity and thyroid hormones in euthyroid postmenopausal women

OBJECTIVE

We aimed to evaluate the association between thyroid hormones and indices of obesity in a sample of euthyroid postmenopausal women.

DESIGN

Cross-sectional study.

METHODS

Serum levels of TSH, free triiodothyronine (FT3), and free thyroxine (FT4) as well as BMI and waist:hip ratio (WHR) were evaluated in 194 healthy euthyroid postmenopausal women. Ultrasonography was used to assess abdominal fat layers (subcutaneous fat (SF), preperitoneal fat (PF), and SF:PF ratio). Indices of adiposity were defined as high vs low depending on the median value of the assessed parameters.

RESULTS

After multivariate adjustment for traditional risk factors, lower FT4 levels and a higher FT3:FT4 ratio predicted higher SF mass (FT4, Exp(β)=0.035, P=0.020 and FT3:FT4, Exp(β)=2.374, P=0.018), whereas higher FT3 predicted higher PF mass (Exp(β)=2.815, P=0.032). Women with FT3:FT4 above the highest quartile had a significantly higher SF mass as compared to women in the lowest quartile (1.81 ± 0.62 cm vs 1.54 ± 0.46 cm, P=0.027). BMI had a positive independent association with TSH (Exp(β)=1.829, P=0.018). Finally, FT3 was significantly associated with SF mass among women with higher BMI (FT3, β=0.259, P=0.040) and women with higher WHR (β=0.309, P=0.020) but not among women with lower BMI or WHR values.

CONCLUSION

Thyroid hormone levels, and in particular FT3, were independently associated with SF and PF in euthyroid postmenopausal women, and this association was mainly evident in women with higher BMIs. On the other hand, among traditional indices of adiposity, only TSH was positively associated with BMI. Larger prospective studies are needed to evaluate the significance of the present findings.

High Body Mass Index Is an Indicator of Maternal Hypothyroidism, Hypothyroxinemia, and Thyroid-Peroxidase Antibody Positivity during Early Pregnancy

Background. Maternal thyroid dysfunction in early pregnancy may increase the risk of adverse pregnancy complications and neurocognitive deficiencies in the developing fetus. Currently, some researchers demonstrated that body mass index (BMI) is associated with thyroid function in nonpregnant population. Hence, the American Thyroid Association recommended screening thyroid function in obese pregnant women; however, the evidence for this is weak. For this purpose, our study investigated the relationship between high BMI and thyroid functions during early pregnancy in Liaoning province, an iodine-sufficient region of China. Methods. Serum thyroid stimulating hormone (TSH), free thyroxine (FT4), thyroid-peroxidase antibody (TPOAb), thyroglobulin antibody (TgAb) concentration, urinary iodine concentration (UIC), and BMI were determined in 6303 pregnant women. Results. BMI ≥ 25 kg/m² may act as an indicator of hypothyroxinemia and TPOAb positivity and BMI ≥ 30 kg/m² was associated with increases in the odds of hypothyroidism, hypothyroxinemia, and TPOAb positivity. The prevalence of isolated hypothyroxinemia increased among pregnant women with BMI > 24 kg/m². Conclusions. High BMI during early pregnancy may be an indicator of maternal thyroid dysfunction; for Asian women whose BMI > 24 kg/m² and who are within 8 weeks of pregnancy, thyroid functions should be assessed especially.

Association Between Thyroid Hormones, Lipids and Oxidative Stress Markers in Subclinical Hypothyroidism

BACKGROUND

Oxidative stress plays a role in the pathogenesis of many chronic diseases. It is recognized in overt hypothyroidism while its existence in subclinical hypothyroidism (SCH) is not well established. The aim of this study was to determine whether there was increased oxidation of lipids and proteins in SCH, and examine their association with lipids and thyroid hormones.

METHODS

Male adults (35-59 years) with SCH (n=467) and euthyroid controls (n=190) were studied. Anthropometric measurements, plasma lipids, thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), total antioxidant capacity (T-AOC), lipid peroxidation products, malondialdehyde (MDA), advanced oxidation protein products (AOPP) and dityrosine concentrations were measured.

RESULTS

Plasma concentrations of MDA were significantly higher (p<0.05) in SCH (8.11±1.39 nmol/mL) compared with euthyroid controls (7.34±1.31 nmol/mL) while AOPP, dityrosine and T-AOC levels were not different. MDA was not associated with TSH (β=-0.019, P=0.759), FT4 (β=-0.062, P=0.323) and FT3 (β=-0.018, P=0.780) in SCH while levels increased with elevated total cholesterol (β=0.229, P=0.001), LDL (β=0.203, P=0.009) and triglycerides (β=0.159, P=0.036) after adjustment for age and body mass index. T-AOC reduced (β=-0.327, P=0.030) with increased MDA in euthyroid controls and not in SCH (β=-0.068, P=0.349), while levels increased with elevated triglycerides in both groups.

CONCLUSIONS

Oxidative stress was increased in subclinical hypothyroidism as evidenced by the elevated lipid peroxidation product, malondialdehyde, while protein oxidation was absent. Thus, reduction of oxidative stress may be beneficial in patients with subclinical hypothyroidism.

Isolated Subclinical Hyperthyrotropinemia in Obese Children: Does Levothyroxine (LT4) Improve Weight Reduction during Combined Behavioral Therapy?

Objective. The study aim was to analyze whether anthropometrical parameters and TSH values in obese children with isolated subclinical hypothyroidism (IsHT) treated with levothyroxine (LT4) and weight reduction program differ from those managed by dietary and behavior counselling only. Material and Methods. 51 obese children with IsHT, who were treated according to the same weight reduction program, were retrospectively analyzed. They were divided into two groups: Group 1, n = 26, and Group 2, n = 25, without or with LT4 therapy, respectively. Changes in anthropometrical (delta BMI z-score) and hormonal (delta TSH) status were analyzed at the first follow-up visit. Results. In both groups significant decrease of TSH and BMI z-score values were noted. TSH normalized in 80.9% of children from Group 1 versus 90.5% from Group 2, p = NS. Delta BMI z-score was insignificantly higher in Group 1 compared to Group 2. Delta TSH was significantly related to initial TSH level in children treated by lifestyle intervention program only. Conclusions. In obese children with sHT dietary-behavioral management intervention contributed to reduction of body mass index, irrespective of levothyroxine use. This finding suggests that moderately elevated levels of TSH are a consequence rather than cause of overweight and pharmacological treatment should be avoided.

Changes in body weight after treatment of primary hypothyroidism with levothyroxine

OBJECTIVE

Surprisingly few studies have examined weight change in hypothyroid patients after initiation of levothyroxine (LT4) therapy. Our study aimed to investigate weight change after initiation of LT4 treatment for primary hypothyroidism.

METHODS

Using electronic medical records from Boston Medical Center, Boston, Massachusetts, we performed a retrospective cohort study between January 1, 2003, and February 1, 2011. Adults ≥18 years of age with newly diagnosed primary hypothyroidism with an initial thyroid-stimulating hormone (TSH) level ≥10 mIU/L were identified. Patients with postsurgical hypothyroidism, thyroid cancer, and a history of radioactive iodine or head/neck irradiation, congestive heart failure, anorexia nervosa, end-stage renal disease, cirrhosis, pregnancy, or use of prescription weight-loss medications were excluded. TSH and weight at diagnosis and up to 24 months after LT4 initiation were collected. Weight change was assessed at the first posttreatment serum TSH level <5 mIU/L.

RESULTS

A total of 101 patients (mean age, 48 ± 15 years; 71% women) were included. Initial median TSH was 18.3 mIU/L (range, 10.1 to 710.5 mIU/L) and initial median weight was 79.6 kg (range 41.5 to 167.5 kg). Posttreatment median TSH level was 2.3 mIU/L (range, 0.04 to 5 mIU/L), and weight change at a median of 5 months (range, 1.1 to 25.6 months) was -0.1 kg (range, -20.6 to 7.7 kg). Initial median body mass index (BMI) of 95 of the patients was 29.3 kg/m2 (range, 19.5 to 56.1 kg/m2), and the median change in BMI was -0.1 kg/m2 (range, -7.1 to 3.3 kg/m2). Only 52% of patients lost weight, with a mean weight loss of 3.8 ± 4.4 kg. Gender, race, education, insurance type, age, initial TSH level, time to normalization of TSH, and initial weight were not associated with changes in weight or BMI.

CONCLUSION

Contrary to popular belief, our study of 101 patients with primary hypothyroidism showed that no significant weight change occurs after initiation of LT4 treatment.

Mechanisms in endocrinology: the crosstalk between thyroid gland and adipose tissue: signal integration in health and disease

Obesity and thyroid diseases are common disorders in the general population and they frequently occur in single individuals. Alongside a chance association, a direct relationship between 'thyroid and obesity' has been hypothesized. Thyroid hormone is an important determinant of energy expenditure and contributes to appetite regulation, while hormones and cytokines from the adipose tissue act on the CNS to inform on the quantity of energy stores. A continuous interaction between the thyroid hormone and regulatory mechanisms localized in adipose tissue and brain is important for human body weight control and maintenance of optimal energy balance. Whether obesity has a pathogenic role in thyroid disease remains largely a matter of investigation. This review highlights the complexity in the identification of thyroid hormone deficiency in obese patients. Regardless of the importance of treating subclinical and overt hypothyroidism, at present there is no evidence to recommend pharmacological correction of the isolated hyperthyrotropinemia often encountered in obese patients. While thyroid hormones are not indicated as anti-obesity drugs, preclinical studies suggest that thyromimetic drugs, by targeting selected receptors, might be useful in the treatment of obesity and dyslipidemia.