Increased leptin/adiponectin ratio relates to low-normal thyroid function in metabolic syndrome

Impact of Weight Reduction on Thyroid Function and Nonalcoholic Fatty Liver among Egyptian Adolescents with Obesity

BACKGROUND

The prevalence of childhood obesity has been increasing worldwide. This may explain the emergence of nonalcoholic fatty liver as the leading cause of liver disease. Several previous studies have addressed the association between thyroid function and nonalcoholic fatty liver disease.

OBJECTIVES

To study the impact of weight reduction through lifestyle modifications in adolescents with obesity.

METHODS

A prospective cohort study was done on 61 adolescents with obesity. Patients were evaluated at the first visit by the full history, clinical examination, and investigations (thyroid profile, lipid profile, liver function tests, HbA1c, and liver ultrasonography) as basal information. The intervention program included a dietary program, increasing physical activity, and decreasing sedentary activity. A postintervention evaluation was done at the end of six months which included anthropometric measures, laboratory results, and ultrasonographic estimation.

RESULTS

It was shown that the mean BMI of the participants had significantly decreased after lifestyle modification from (32.05 ± 3.36 kg/m2) to (28.1 ± 2.77 kg/m2) (P < 0.001). It also showed that the percentage of studied adolescents with elevated TSH decreased from 47.5% to 19.7% after the weight reduction program. Improvement was also achieved in the lipid profile and liver functions. The percentage of studied adolescents with ultrasound appearance of NAFLD decreased from 31.1% to 26.2% after weight reduction.

CONCLUSIONS

Lifestyle modification positively influences the metabolic derangement in obesity without medical treatment. ΔTSH is a significant predictor of the change in BMI z-score. It is also possible that hepatic steatosis affects thyroid function rather than the other way around.

Obesity and Thyroid Axis

Development of obesity is primarily the result of imbalance between energy intake and energy expenditure. Thyroid hormones influence energy expenditure by regulating cellular respiration and thermogenesis and by determining resting metabolic rate. Triiodothyronine influences lipid turnover in adipocytes and impacts appetite regulation through the central nervous system, mainly the hypothalamus. Thyroid-stimulating hormone may also influence thermogenesis, suppress appetite and regulate lipid storage through lipolysis and lipogenesis control. Subclinical hypothyroidism may induce changes in basal metabolic rate with subsequent increase in BMI, but obesity can also affect thyroid function via several mechanisms such as lipotoxicity and changes in adipokines and inflammatory cytokine secretion. The present study investigated the complex and mutual relationships between the thyroid axis and adiposity.

Effect of left gastric artery embolization on obesity and ghrelin/leptin levels in pigs

OBJECTIVE

To investigate the influence of left gastric artery embolization (LGAE) on obesity and Ghrelin/Leptin levels in pigs.

METHODS

Healthy female Wuzhishan piglets aged 3-4 months were allocated into obesity + LGAE group, obesity group, control group (fed with a normal diet; n=8 for each group). Body weight, serum Ghrelin, Leptin, glucose and insulin levels were compared before surgery, 1 month and 3 months after surgery.

RESULTS

Piglets in obesity group and obesity + LGAE group were heavier than those in control group before and 1 month after surgery (P<0.001), and in obesity group were heavier than those in obesity + LGAE group 1 month after surgery (P<0.05). A significant decrease in body weight was observed in obesity + LGAE group 3 months after surgery (P<0.05), and the obesity group showed heavier weight than the other two groups (P<0.001). Ghrelin levels in obesity group and obesity + LGAE group were higher than those in control group before and 1 month after surgery (P<0.001), and in obesity group were higher than those in obesity + LGAE group 1 month after surgery (P<0.05). They showed an evident decrease in obesity + LGAE group 3 months after surgery (P<0.05), and in obesity group were higher than that in the other two groups (P<0.01). Leptin levels in obesity group and obesity + LGAE group were higher than those in control group before surgery (P<0.01) and 1 month after surgery (P<0.05). They decreased significantly in obesity + LGAE group 3 months after surgery (P<0.01), and in obesity group were higher than those in the other two groups (P<0.01).

CONCLUSION

LGAE greatly contributes to weight loss possibly by reducing the secretion of Ghrelin and Leptin.

Genome-wide meta-analysis identifies novel loci associated with free triiodothyronine and thyroid-stimulating hormone

PURPOSE

Thyroid hormones are essential for the normal function of almost all human tissues, and have critical roles in metabolism, differentiation and growth. Free triiodothyronine (fT3), free thyroxine (fT4) and thyroid-stimulating hormone (TSH) levels are under strong genetic influence; however, most of the heritability is yet unexplained.

METHODS

In order to identify novel loci associated with fT3, fT4 and TSH serum levels we performed a genome-wide meta-analysis of 7 411 206 polymorphisms in up to 1731 euthyroid individuals from three Croatian cohorts from Dalmatia region: two genetically isolated island populations and one mainland population. Additionally, we also performed a bivariate analysis of fT3 and fT4 levels.

RESULTS

The EPHB2 gene variant rs67142165 reached genome-wide significance for association with fT3 plasma levels (P = 9.27 × 10^-9) and its significance was confirmed in bivariate analysis (P = 9.72 × 10^-9). We also found a genome-wide significant association for variant rs13037502 upstream of the PTPN1 gene and TSH plasma levels (P = 1.67 × 10^-8).

CONCLUSION

We identified a first genome-wide significant variant associated with fT3 plasma levels, as well as a novel locus associated with TSH plasma levels. These findings are biologically relevant and enrich our knowledge about the genetic basis of pituitary-thyroid axis function.