Interplay between metabolic and thyroid parameters in obese pubertal children. Does visceral adipose tissue make the first move?

Objectives: The mechanisms of obesity-associated thyroid dysfunction in children are incompletely deciphered. We aimed to evaluate whether visceral adipose tissue (VAT), insulin resistance (IR), inflammation, oxidative stress (OS) are involved in thyroid morpho-functional changes in pubertal obese children. Methods: We recruited 43 obese pubertal children without history of thyroid pathology. Metabolic and thyroid parameters (visceral fat thickness [VFT], waist/hip ratio [WHR], waist/height ratio [WHtR], insulin, glucose, liver parameters, thyroid stimulation hormone [TSH], free thyroxine [FT4], free triiodothyronine [FT3], thyroid and abdominal ultrasonography) were evaluated. Serum monocyte chemoattractant protein-1 (MCP-1) and malondialdehyde (MDA) levels were quantified as markers of inflammation and OS. Results: VFT correlated positively both with WHR (p= 0.034) and the presence of thyroid nodules (p= 0.036). WHR associated with TSH (p= 0.005), FT3/FT4 (p= 0.033) and was independently associated with FT3/FT4 increase (p< 0.001). HOMA-IR increased with visceral obesity (waist circumference, p= 0.001; WHR, p= 0.018; WHtR: p< 0.001), hepatic impairment (alanine aminotransferase, p= 0.019) and hepatic steatosis (HS; p= 0.013) and correlated positively with FT3/FT4 (p= 0.036). TSH was significantly higher in subjects with HS versus those without HS (p= 0.007) and logistic regression analysis identified TSH as a risk factor for HS (p= 0.014). MDA correlated positively with MCP-1 (p= 0.021). Conclusion: VAT and IR may be responsible for changes in thyroid parameters associated with obesity: elevated TSH, FT3/FT4 levels and increased prevalence of thyroid nodules. WHR was predictive of increased FT3/FT4. In obese children, there is an interdependent relationship between HS and thyroid function.

Serum homocysteine levels, oxidative stress and cardiovascular risk in non-alcoholic steatohepatitis.

INTRODUCTION: Hyperhomocysteinemia is considered an independent risk factor for cardiovascular disease. Oxidative stress is one of the major pathogenic mechanisms in non-alcoholic fatty liver disease and atherosclerosis. AIM: Our study aimed to evaluate serum homocysteine levels and oxidative stress in patients with biopsy-proven non-alcoholic steatohepatitis and possible association with cardiovascular risk measured by carotid artery intima-media thickness (c-IMT). PATIENTS AND METHODS: 50 patients with non-alcoholic steatohepatitis and 30 healthy controls, age and gender matched, were recruited. Lipid profile, liver biochemical markers, serum homocysteine, vitamins B6 and B12, folic acid, glutathione (reduced and total), erythrocyte superoxide dismutase, whole blood glutathione peroxidase, malondialdehyde and carotid intima-media thickness were assayed. RESULTS: Patients had an altered lipid profile and liver biochemical markers; carotid intima-media thickness and serum homocysteine levels were significantly higher compared to controls, but there were no differences in folate, B12 and B6 vitamins levels. Patients had significantly lower levels of glutathione peroxidase activity, total and reduced glutathione and higher levels of malondialdehyde, but unchanged superoxide dismutase activity compared to control group. Also, serum homocysteine level showed significant positive correlation with waist circumference, body mass index, free cholesterol, triglycerides, LDL-cholesterol, amino transferases and negative correlation with reduced and total glutathione, superoxide dismutase and γ-GT. CONCLUSION: Non-alcoholic steatohepatitis is an independent cardiovascular risk factor, associated with elevated homocysteine levels, oxidative stress and c-IMT. c-IMT could be used as an indicator of early atherosclerotic changes initiated by dyslipidemia and oxidative stress, while higher level of homocysteine might be an effect of liver damage.