Changes in lifestyle improve body composition, thyroid function, and structure in obese children

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.

Thyroid Homeostasis After Bariatric Surgery in Obese Cases

BACKGROUND

The aim of this study was to determine changes in thyroid hormones and morphology with weight loss after bariatric surgery in obese patients.

METHODS

This prospective study was performed in our endocrinology and surgery clinic. Pre- and post-bariatric surgery thyroid function tests and thyroid ultrasonography parameters were compared.

RESULTS

Four hundred seventy-two patients were included in the study. Mean weight loss after surgery was 30.7 ± 5.1 kg. TSH levels decreased statistically significantly parallel with weight loss and decreased BMI (p = 0.025) after bariatric surgery. However, no statistically significant change was observed in fT4 or fT3 levels (p > 0.05). A significant increase in thyroid parenchyma echogenicity, correlated with weight loss and time elapsed since surgery, was detected at ultrasonography (US) grayscale histogram analysis compared with muscle echogenicity (p = 0.032). An increase in echogenicity was even detected in patients with isoechoic thyroid parenchyma before surgery. Fasting insulin and HOMA-IR levels decreased after surgery (p = 0.010 and p = 0.001, respectively). Patients were divided into three groups based on weight loss. In group 3, preoperative TSH of 4.1 ± 0.7 decreased to 1.6 ± 0.7 postoperatively (p = 0.001), while preoperative HOMA-IR of 4.9 ± 1.9 decreased to 2.4 ± 0.8 postoperatively (p = 0.001).

CONCLUSIONS

Obesity causes thyroid hormone resistance through a mechanism similar to insulin resistance and leads to an increase in TSH similar to hyperinsulinemia. Our findings show that echogenicity at thyroid US increases in line with weight loss following bariatric surgery.

Weight loss efficacy of alternate day fasting versus daily calorie restriction in subjects with subclinical hypothyroidism: a secondary analysis

This study compared the weight loss efficacy of alternate-day fasting (ADF) versus daily calorie restriction (CR) in adults with subclinical hypothyroidism. After 6 months, body weight decreased (P < 0.001) similarly by ADF (-7% ± 1%) and CR (-8% ± 2%). Insulin resistance decreased (P < 0.05) more by ADF versus CR. Free thyroxin and thyroid-stimulating hormone remained unchanged. Thus, ADF and CR produce similar weight loss in this population, without affecting thyroid hormone levels. Novelty Intermittent fasting and daily restriction produce similar reductions in body weight in subjects with subclinical hypothyroidism.

ASSOCIATIONS OF THYROID VOLUME AND FUNCTION WITH CHILDHOOD OBESITY

CONTEXT

The links between obesity and thyroid function or thyroid volume in children are still controversial with limited available data.

OBJECTIVE

This study aimed to examine thyroid function and volume in obese Turkish school-age children in comparison to normal-weight children.

DESIGN

Cross-sectional study.

SUBJECTS AND METHODS

One hundred obese children (47 boys, 53 girls; mean age 10.34±2.79 years) with a body mass index (BMI) above 95th percentile, and 100 normal-weight children (42 boys, 58 girls; 10.34±2.79 years) were included. The study parameters were BMI z score (Z-BMI), body surface area (BSA), thyroid volume, free thyroxine (fT4) and thyroid stimulating hormone (TSH) levels.

RESULTS

The mean TSH and fT4 levels did not show a significant difference between obese and normal-weight children (p>0.05). The mean thyroid volume was higher in obese children (6.46±5.84 and 4.64±1.44, respectively; p=0.043). fT4 correlated negatively with Z-BMI in both normal-weight and obese children (r=-0.285, p=0.004 and r=-0.289, p=0.004, respectively). Thyroid volume, on the other hand, correlated positively with Z-BMI, again in both normal-weight and obese children (r=0.657, p<0.001 and r=0.444, p<0.001, respectively). Similar associations were found for BSA.

CONCLUSIONS

Thyroid volume correlated positively and fT4 correlated negatively with Z-BMI and BSA, in both obese and normal-weight school-age children, whereas TSH appears to be independent of these parameters.

Cardiovascular Risk Factors in Children and Adolescents with Subclinical Hypothyroidism

BACKGROUND

Subclinical hypothyroidism (SCH) is a commonly encountered entity in day-to-day clinical practice and has been associated with adverse cardiovascular risk profile in adults and children. Data on children and adolescents with SCH, from India, are limited.

MATERIALS AND METHODS

This study was a cross-sectional case-control study, conducted at a tertiary care center in Northeast India. Twenty-seven children and adolescents aged 11 ± 2.4 years with SCH and thyroid-stimulating hormone >7.5 mIU/L were included in the study along with 20 age-, gender-, and height-matched controls. Multiple clinical, biochemical, and radiological cardiovascular risk factors were assessed and compared between the two groups.

RESULTS

Body mass index (BMI) (P = 0.048), waist circumference (P = 0.008), waist to height ratio (P = 0.007), low-density lipoprotein cholesterol (P = 0.04), triglycerides (TGs) (P = 0.038), TGs to high-density lipoprotein (HDL) cholesterol ratio (P = 0.005), non-HDL cholesterol (P = 0.019), fasting insulin (P = 0.006), and homeostasis model assessment of insulin resistance (P = 0.007) were found to be significantly higher while free T4 (P = 0.002) and HDL cholesterol (P = 0.019) were found to be significantly lower in SCH subjects compared to controls. On multiple regression analysis, BMI was found to have significant association with multiple cardiovascular risk factors.

CONCLUSION

Children and adolescents with SCH were found to have adverse cardiovascular risk profile. Long-term follow-up studies are required to assess the clinical significance of these findings and requirement for therapy.

Hypothyroidism and obesity: An intriguing link

According to common perception, hypothyroidism is held responsible for obesity. However, linking them causally is controversial. Overt hypothyroidism is associated with modest weight gain, but there is a lack of clarity regarding subclinical hypothyroidism. Novel view indicates that changes in thyroid-stimulating hormone (TSH) could well be secondary to obesity. The increasing prevalence of obesity further confounds definition of normal TSH range in population studies. Thyroid autoantibody status may help in establishing the diagnosis of subclinical hypothyroidism in obesity. High leptin levels may play a role in the hyperthyrotropinemia of obesity and also increase susceptibility to thyroid autoimmunity and subsequent hypothyroidism. There is at most a modest effect of L-T4 treatment in overt hypothyroidism in inducing weight loss; benefit in subclinical hypothyroidism is not established with no data supporting thyroid hormone use in euthyroid obese patients.

Ultrasound image of the thyroid gland in obese children

Obesity as a disease of affluence also affects younger children. Numerous observations suggest a link between excessive body weight and thyroid function disorders. Subclinical hypothyroidism has been diagnosed increasingly frequently in patients with obesity. A growing number of papers also point to morphological changes of the thyroid gland in the ultrasound examination in obese children. These reports mainly concern changes in echogenicity. The present paper discusses the most important aspects of this topic on the basis of the literature as well as containing a brief analysis based on own experiences.

Isolated hyperthyrotropinemia in childhood obesity and its relation with metabolic parameters

PURPOSE

The aim of the presented study was to evaluate the prevalence of isolated hyperthyrotropinemia (IH) in obese children and the relation between anthropometric and metabolic parameters.

METHODS

Hospital records of the children, who presented to the Pediatric Endocrinology outpatient clinic of our institution with obesity, and age and gender-matched healthy children, who had undergone thyroid function test for any reason were retrospectively reviewed.

RESULTS

The prevalence of IH was significantly higher in the obese group than in the controls (9.2 and 3.8 %, respectively). Body mass index-standard deviation score (BMI-SDS), thyroid-stimulating hormone (TSH), lipid parameters were significantly different in the obese group than in the control group. A positive correlation between TSH and BMI-SDS and negative correlation between TSH and free T4 (fT4) levels were found in obese subjects. Stepwise multiple linear regression analysis confirmed that BMI-SDS, fT4 and triglyceride levels were the strongest independent variables correlated with TSH level in obese subjects (r (2) = 0.046, p = 0.001).

CONCLUSIONS

IH prevalence is higher in obese children as compared to healthy children and the increase in TSH level correlates negatively with serum fT4 and positively with BMI-SDS and triglyceride levels in obese children.

2014 European thyroid association guidelines for the management of subclinical hypothyroidism in pregnancy and in children

This guideline has been produced as the official statement of the European Thyroid Association guideline committee. Subclinical hypothyroidism (SCH) in pregnancy is defined as a thyroid-stimulating hormone (TSH) level above the pregnancy-related reference range with a normal serum thyroxine concentration. Isolated hypothyroxinaemia (defined as a thyroxine level below the 2.5th centile of the pregnancy-related reference range with a normal TSH level) is also recognized in pregnancy. In the majority of SCH the cause is autoimmune thyroiditis but may also be due to iodine deficiency. The cause of isolated hypothyroxinaemia is usually not apparent, but iodine deficiency may be a factor. SCH and isolated hypothyroxinaemia are both associated with adverse obstetric outcomes. Levothyroxine therapy may ameliorate some of these with SCH but not in isolated hypothyroxinaemia. SCH and isolated hypothyroxinaemia are both associated with neuro-intellectual impairment of the child, but there is no evidence that maternal levothyroxine therapy improves this outcome. Targeted antenatal screening for thyroid function will miss a substantial percentage of women with thyroid dysfunction. In children SCH (serum TSH concentration >5.5-10 mU/l) normalizes in >70% and persists in the majority of the remaining patients over the subsequent 5 years, but rarely worsens. There is a lack of studies examining the impact of SCH on the neuropsychological development of children under the age of 3 years. In older children, the evidence for an association between SCH and impaired neuropsychological development is inconsistent. Good quality studies examining the effect of treatment of SCH in children are lacking.

Reference ranges for thyroid hormones in normal Italian children and adolescents and overweight adolescents

BACKGROUND

As thyroid hormones are essential for normal pubertal growth and sexual development, TSH, free T₃ (FT₃) and free T₄ (FT₄) levels undergo progressive modification during childhood and puberty.

AIM

To establish thyroid hormone reference ranges in pre-pubertal children, pubertal adolescents, and adults and to evaluate any differences in thyroid function between overweight and normalweight pubertal subjects.

SUBJECTS AND METHODS

Chemiluminescent microparticle immunoassay was used to analyze TSH, FT₃ and FT₄ concentrations in serum samples from 508 children and adolescents aged 6 to 18 yr and 100 healthy adults aged 30 to 60 yr, and from 68 overweight pubertal adolescents. As data were not normally distributed, we compared them through non-parametric tests for independent samples and the reference ranges were assumed to lie between the 2.5th and 97.5th percentile.

RESULTS

We found a progressive and significant reduction in TSH, FT₃, and FT₄ levels in the three groups with increasing age. TSH levels were significantly higher in overweight patients than in the normal-weight group, but there were no significant differences for FT₃ or FT₄.

CONCLUSIONS

This study revealed significant differences in levels of thyroid hormone between different age groups and allowed us to establish normal reference ranges for pre-pubertal children between 0.87-5.19 mIU/l for TSH, 4.75-8.59 pmol/l for FT₃, and 13.09-20.61 pmol/l for FT₄, and for pubertal adolescents between 0.76- 4.51 mIU/l for TSH, 4.26-8.46 pmol/l for FT₃ and 10.94-19.09 pmol/l for FT₄.

Thyroid function and obesity

Nowadays, childhood obesity is one of the biggest health emergencies in the developed countries. Obesity leads to multiple metabolic alterations which increase the risk of developing diabetes and cardiovascular diseases. Thyroid function has been often described as altered in obese children, however, it is not clear whether the altered thyroid function is the cause or the consequence of fat excess. On the other hand, thyroid structure seems also to be affected. Nevertheless, both functional and structural alterations seem to improve after weight loss and therefore no treatment is needed.