Influence of Obesity Parameters on Different Regional Patterns of Lymph Node Metastasis in Papillary Thyroid Cancer

OBJECTIVE

Obesity increases risk of thyroid cancer. However, the association between obesity and the progression of papillary thyroid cancer (PTC) remains controversial. This retrospective study aimed to explore the relationship between obesity and regional patterns of lymph node metastasis (LNM) in PTC.

METHODS

We retrospectively reviewed data from 1015 patients with PTC. We calculated obese parameters, such as body mass index (BMI), body fat percentage (BFP), and body surface area (BSA). Logistic regression models were used to assess associations between obese parameters and the rate of lymph node metastasis (LNM), number of LNM, pattern of LNM, and lymph node ratio (LNR).

RESULTS

Higher BMI was not associated with different regional patterns of LNM in PTC. In men with PTC, high BFP was an independent predictor of total LNM, central lymph node metastasis (CLNM), total lateral lymph node metastasis (LLNM), multiple lateral lymph node metastasis, and simultaneous metastasis in lateral compartment. In addition, male patients with high BFP had higher central LNR and higher number of CLNM. For women, high BSA was an independent predictor of LLNM and level IV metastasis. Female patients with high BSA had higher number of CLNM.

CONCLUSION

BFP and BSA, possibly influenced by gender, were positively associated with the number and risk of LNM in different regions of PTC patients. However, BMI was not the predictor for aggressiveness of PTC in terms of LNM. Clinical decision-making for regional LNM in PTC patients should consider the factor of obesity.

The Association Between Serum Thyrotropin Within the Reference Range and Metabolic Syndrome in a Community-Based Chinese Population

PURPOSE

We aimed to ascertain the association between thyrotropin (TSH) levels in euthyroid state and the prevalence of metabolic syndrome (MetS) in a community-based Chinese population.

PARTICIPANTS AND METHODS

Based on a large and well-characterized community cohort in Beijing, China, 1831 men and 1742 women with serum TSH levels within the reference range (0.50-4.78 µIU/mL) were stratified by quartiles of TSH (Q1-4). MetS was identified according to the criteria of International Diabetes Federation guidelines. Poisson regression models were used to estimate the association between serum TSH and the prevalence of MetS and its components before and after adjustment for potential confounding factors. The reported association was measured using the prevalence ratio (PR) with its respective 95% confidence interval (95% CI).

RESULTS

The prevalence of MetS in euthyroid population across TSH quartiles (Q1-4) was 38.9%, 44.6%, 41.0%, and 47.7%, respectively, in men (P = 0.045), and 47.7%, 46.6%, 46.9%, and 54.6%, respectively, in women (P = 0.032). Compared with the reference group TSH-Q1, the prevalence of MetS was higher among TSH-Q4 group both in men (PR = 1.27; 95% CI: 1.09, 1.48, P = 0.002) and women (PR = 1.21; 95% CI: 1.07, 1.37, P = 0.003) even after adjustment for age, lifestyle factors, serum levels of free triiodothyronine (FT3), and free thyroxine (FT4). Most of the components of MetS were common in higher serum TSH levels within the normal range.

CONCLUSION

The prevalence of MetS and most of its components increased in the higher TSH group in euthyroid Chinese population.

Association between serum thyrotropin within the euthyroid range and obesity

The relationship between variations in thyroid function and indices of obesity remains a focus of debate. To explore the associations between thyroid function within the normal range and obesity and to evaluate potential modifying factors, we analyzed a large and well-characterized community cohort in Beijing, China, containing 1,816 men and 1,774 women with serum thyrotropin (TSH) levels within the reference range (0.55-4.78 μIU/mL). Associations between TSH levels and BMI were identified using correlation analysis, ANOVA and Chi-square tests. Logistic regression analyses were used to estimate the impact of serum TSH on obesity before and after adjustment for possible confounding factors. The mean serum TSH was 2.04 ± 0.94 μIU/mL. TSH within the reference range was positively associated with BMI in both genders. Compared with euthyroid adults whose TSH was in the middle quartiles (TSH 1.30-2.60 μIU/mL) of the reference range, the odds of obesity (BMI ≥ 28.0 kg/m²) and severe obesity (BMI ≥ 33.0 kg/m²) was 38% (OR = 1.38, 95% CI 1.17-1.64) and 58% (OR = 1.58, 95% CI 1.12-2.21) more likely, respectively, among those with TSH in the upper quartile. For women, postmenopausal subjects with lower TSH levels had a lower risk of severe obesity (OR = 0.42, 95% CI 0.20-0.91) than those in the middle TSH quartile. Positive associations were found between serum TSH within the euthyroid range and obesity, and menopause showed a significant influence on the relationship between TSH level and severe obesity.

Changes in trophoblasts gene expression in response to perchlorate exposition

Contaminated water with chlorates is a public health problem associated with iodine deficiency. Epidemiological evidence shows that iodine deficiency is a risk factor for preeclampsia (PE). In this study we use human BeWo trophoblast cells exposed to perchlorate (KClO₄) and changes in gene expression were analyzed by microarrays, quantitative RT-PCR (qRT-PCR) and immunoblot. The microarray analysis identified 48 transcripts up-regulated and 112 down-regulated in comparison with non-exposed trophoblast. The qRT-PCR analysis confirmed changes in GAS7, PKP2, Emilin, Dynatic 3, protocadherins 11, 15, gamma A12, EGFR, SAFB1, ACE2, ANXA2, Apoliprotein E, SREBF1, and C/EBP-β. KClO₄ exposition decreased the mRNA and protein of C/EBP-β and GPX4. Also, we observed a nuclear translocation of HIF1α protein, and increase in both Snail and ACE2 protein by immunoblot. These effects were accompanied by an increases in ROS and nitric oxide. In conclusion, our results show that exposure to KClO₄ alters genes involved in migration, adhesion, differentiation, and correlate with the increase of oxidative stress and nitric oxide production in trophoblast cells. It is possible that iodine deficiency is associated with these processes. However, further studies are required to corroborate the role of iodine in trophoblast cells.

The importance of anthropometric paremeters in patients with subclinical hypothyroidism

Introduction: The concept of subclinical thyroid disease appeared in the 1980s when sensitive procedures for the measurement of the thyroid-stimulating hormone in the serum were introduced. Subclinical hypothyroidism is defined by the finding of elevated serum TSH concentrations with normal thyroid hormone levels. The incidence of subclinical hypothyroidism with increased cardiovascular risk has not yet been fully clarified. The aim of the study was to identify anthropometric parameters that may indicate an increased cardiometabolic risk in patients with subclinical hypothyroidism. Method: The study will include 140 patients aged 18-65, with 105 patients with subclinical hypothyroidism and a control group of 35 healthy, normally nourished subjects without subclinical hypothyroidism. A program of research will be carried out in all patients and it will include: detailed anamnesis and physical examination, anthropometric measurements (weight measurements, body height, waist circumference, hip circumference, body weight mass measurement by the bioelectrical impedance analysis method (%BFP), calculation of: body mass index (BMI), waist-to-hip circumference ratio (WC/HC), waist-to-height ratio (WC/Ht) and laboratory testing (FT3, FT4, TSH). Results: Examinees with subclinical hypothyroidism had statistically significantly elevated mean TSH values (6.87 + 1.34 mIU/ml) compared to TSH euthyroid examinees (1.9 + .88 mIU/ml). The mean age of subjects with subclinical hypothyroidism was 44.15 ± 11.23 years (MA = 43 years), and in subjects without subclinical hypothyroidism, 33.80 ± 10.60 years (MA = 33 years). In relation to the control group (euthyroid patients), patients with subclinical form of hypothyroidism had higher average mean values and statistically significantly higher incidence of elevated values: BMI (T test = 7.465, p < 0.0001; 2 = 35.977, p < 0.0001), %BFP (T test = 8.594, p < 0.0001; 2 = 44.956, p < 0.0001), WC (T test = 6.262, p < 0.0001; 2 = 48.865, p < 0.0001), and WC/Ht ratio (T test = 7.372, p < 0.0001; 2 = 39.175, p < 0.0001). The WC/HC ratio in the group with subclinical hypothyroidism was higher than in the group without subclinical hypothyroidism, but not statistically significant (T test = -0.946, p = ns; 2 = 0.622, p = 0). Conclusion: In the subclinical form of hypothyroidism, changes in the degree of nutrition and body weight can already be recorded, which, among other things, contributes to the development of increased cardiometabolic risk.

Delayed TSH recovery after dose adjustment during TSH-suppressive levothyroxine therapy of thyroid cancer

BACKGROUND

Delayed thyroid-stimulating hormone (TSH) recovery during treatment of Graves' disease is caused by long-term excessive thyroid hormone, which results in downregulation of pituitary thyrotrophs. However, it is unknown whether delayed TSH recovery exists after levothyroxine (LT4) dose reduction in patients with differentiated thyroid cancer (DTC) after long-term TSH suppression.

METHODS

We retrospectively reviewed 97 DTC patients with LT4 dose reduction after long-term TSH suppression. TSH levels at baseline (point 1), 6 months (point 2) and 12-18 months (point 3) after LT4 dose reduction were compared. A delayed TSH recovery group whose TSH levels changed to upper target TSH category (2015 revised ATA guidelines) from point 2 to point 3 was identified, and risk factors were analysed.

RESULTS

The median TSH level at point 3 was significantly higher than that of point 2 (0.17 vs 0.09 mIU/L; P<.001). The delayed TSH recovery group (44.3%) showed increased body weight (60.84 vs 62.73 kg; P=.01), while normal response group did not. Greater reduction (%) in the LT4 dose per weight [HR 1.10, 95% CI (1.00-1.22), P=.04] and higher BMI before thyroid surgery [1.19, 1.03-1.38, P=.01] predicted the occurrence of delayed TSH recovery, while higher dose of LT4 per weight after reduction showed preventive effect [HR 0.01, 95% CI (0.00-0.54); P=.02].

CONCLUSIONS

Delayed TSH recovery was common during LT4 dose reduction after long-term TSH suppression for DTC management. Six months may not be enough for TSH recovery and to evaluate thyroid hormone status by serum TSH.

Association between thyroid hormones, thyroid antibodies and insulin resistance in euthyroid individuals: A population-based cohort

AIM

The association between insulin resistance and thyroid function in euthyroid subjects has not yet been clarified. This study aimed to investigate the association between thyroid function within the normal reference range and insulin resistance in participants of the Tehran Thyroid Study (TTS).

METHODS

This cross-sectional study was conducted within the framework of the TTS. Of 5786 subjects aged ≥ 20 years, 2758 euthyroid subjects free of thyroid disorders, diabetes, chronic kidney disease and cardiovascular disease, and not taking steroids and lipid-lowering agents, were included. Serum concentrations of free thyroxine (FT4) and TSH were measured. The homoeostasis model assessment index for insulin resistance (HOMA-IR) was used to evaluate IR.

RESULTS

On linear regression analysis, a negative association was found between serum FT4 levels and HOMA-IR in the model with age, smoking and physical activity (B = -0.09, P < 0.001) and in the WC-adjusted model with age, smoking and physical activity for men (B = -0.06, P < 0.01). In addition, there was a positive association between serum TSH levels and HOMA-IR in both models [with age, smoking and physical activity (B = 0.07, P = 0.006), and age, smoking, physical activity and adjusted for WC (B = 0.05, P = 0.01)] that was not more significant on logistic regression analysis. In women, neither serum FT4 nor TSH levels were associated with HOMA-IR; the prevalence of IR decreased from 27.2 to 19.1 with increasing tertiles of FT4 only in men (P = 0.01). No significant differences were observed in HOMA-IR and its components between thyroid peroxidase antibody (TPOAb)-negative and -positive groups. Also, it was found that metabolically healthy but obese (MHO) subjects had higher levels of TSH than individuals who were MONW (metabolically obese but normal weight; P < 0.01).

CONCLUSION

Low FT4 was independently associated with IR in healthy euthyroid Iranian men.

Impact of body mass index on thyroid functions in Indian children

OBJECTIVE

There is controversy about the relation of thyroid functions and body mass index. The present study was aimed to assess the relationship between thyroid function and body mass index in Indian school children.

DESIGN

Population survey.

PATIENTS

Data were collected from 25 schools in 19 cities across five different geographical zones of India. Children, who consented, were evaluated for anthropometry and blood tests. Children were categorized as overweight and obese based on standard BMI criteria.

MEASUREMENTS

Serum samples were analysed for free T3, free T4, TSH and anti-TPO antibodies.

RESULTS

A total of 13,691 children in the age group of 5-18 years formed the study population. The mean age and mean BMI were 11·9 ± 3·0 years and 18·48 ± 3·89 kg/m² respectively. Among these, 2119 (15·5%) children were overweight and 536 (3·9%) were obese. Subclinical hypothyroidism was present in 943 (6·9%) children.FT3 and TSH levels increased and FT4 levels decreased with increasing BMI in euthyroid boys and girls. Prevalence of SCH was significantly higher in obese/overweight children (9·0%, vs 6·5%; P = 0·034) as compared with normal BMI children.

CONCLUSIONS

Serum FT3 and TSH were positively while FT4 was negatively associated with BMI in apparently healthy euthyroid children.

The interconnections between obesity, thyroid function, and autoimmunity: the multifold role of leptin

BACKGROUND

There is increasing evidence that changes in thyroid function are associated with obesity, a condition associated with a chronic low-grade state of inflammation. Meanwhile, recent data have disclosed a relation between obesity and thyroid autoimmunity, with the adipocyte hormone leptin appearing to be the key factor linking these two conditions.

SUMMARY

Leptin has variably been implicated in thyroid function, while recent findings suggest that leptin resistance may mitigate leptin deficiency and enhance autoimmunity in obese subjects via mechanisms operating independently of thyroid function. The development of resistance to the weight-lowering effects of leptin in obesity might well be initiated by activation of inflammatory signaling, which substantially contributes to the derangement of immune response and propagation of autoimmunity in susceptible individuals.

CONCLUSIONS

Regulation of inflammasome-derived cytokines in obesity is an important step in controlling the trigger of thyroid autoimmunity. The clarification of the pathways may offer innovative therapeutic targets in obesity and thyroid autoimmunity.

Evidence of mitochondrial dysfunction in obese adolescents

AIM

Although obesity and weight gain generally are anticipated to be caused by an imbalance between energy intake and energy expenditure, the significance of thyroid hormones (TH) remains unclear. Examination of mitochondrial function may reflect intracellular thyroid hormone effect and elucidate whether a lower metabolic rate is present.

METHODS

In a group of 34 obese adolescents (age <16 years and body mass index above the age-related 95th percentile), and an age- and gender-matched group of 32 lean adolescent, thyroid stimulating hormone (TSH) and basal oxygen consumption were measured and mitochondrial function in peripheral blood monocytes was determined by flow cytometry.

RESULTS

Significant increase in TSH (3.06 +/- 1.56 mU/L vs. 2.33 +/- 0.91 mU/L, p < 0.05) and a decrease in VO2 (129 +/- 16 mL O2/m(2)*min vs. 146 +/- 15 mL O2/m(2)*min, p < 0.05) were observed in obese adolescents compared with lean adolescents. Flow cytometry analysis demonstrated a lower mitochondrial mass (6385 +/- 1962 a.u. vs. 7608 +/- 2328 a.u., p < 0.05) and mitochondrial membrane potential (11426 +/- 3861 a.u. vs. 14017 +/- 5536 a.u., p < 0.05) in obese adolescents compared with lean adolescents. These results are even more pronounced in adolescents with obese mothers.

CONCLUSION

In obese adolescents, the increased TSH and lowered VO2 propose a lowered basal metabolic rate and the impaired mitochondrial function suggests a decreased thyroid hormone stimulation of mitochondrial energy production. The maternal in-heritage is suggestive of a basal metabolic defect or mitochondrial resistance for TH.