Thyroid function in obese children with non-alcoholic fatty liver disease

Thyroid hormone action and liver disease, a complex interplay

Thyroid hormone action is involved in virtually all physiological processes. It is well known that the liver and thyroid are intimately linked, with thyroid hormone playing important roles in de novo lipogenesis, beta-oxidation (fatty acid oxidation), cholesterol metabolism, and carbohydrate metabolism. Clinical and mechanistic research studies have shown that thyroid hormone can be involved in chronic liver diseases, including alcohol-associated or NAFLD and HCC. Thyroid hormone action and synthetic thyroid hormone analogs can exert beneficial actions in terms of lowering lipids, preventing chronic liver disease and as liver anticancer agents. More recently, preclinical and clinical studies have indicated that some analogs of thyroid hormone could also play a role in the treatment of liver disease. These synthetic molecules, thyromimetics, can modulate lipid metabolism, particularly in NAFLD/NASH. In this review, we first summarize the thyroid hormone signaling axis in the context of liver biology, then we describe the changes in thyroid hormone signaling in liver disease and how liver diseases affect the thyroid hormone homeostasis, and finally we discuss the use of thyroid hormone-analog for the treatment of liver disease.

The Effect and Potential Mechanism Analysis of Growth Hormone-Secreting Pituitary Adenomas on Thyroid Function

OBJECTIVE

Current studies on the effect of high growth hormone (GH)/insulin-like growth factor (IGF)-1 on thyroid function are inconsistent. The aim was to explore the effect and potential mechanism of high GH/IGF-1 on thyroid function by analyzing the changes of thyroid function in patients with growth hormone-secreting pituitary adenoma (GHPA).

METHODS

This was a retrospective cross-sectional study. Demographic and clinical data of 351 patients with GHPA who were first admitted to Beijing Tiantan Hospital, Capital Medical University, from 2015 to 2022 were collected to analyze the relationship between high GH/IGF-1 levels and thyroid function.

RESULTS

GH was negatively correlated with total thyroxine (TT4), free thyroxine (FT4), and thyroid-stimulating hormone (TSH). IGF-1 was positively correlated with total triiodothyronine (TT3), free triiodothyronine (FT3), and FT4 and negatively correlated with TSH. Insulin-like growth factor-binding protein (IGFBP)-3 was positively correlated with TT3, FT3, and FT3:FT4 ratio. The FT3, TT3, TSH, and FT3:FT4 ratio of patients with GHPA and diabetes mellitus (DM) were significantly lower than those with GHPA but without DM. With the increase of tumor volume, thyroid function gradually decreased. GH and IGF-1 were correlated negatively with age in patients with GHPA.

CONCLUSION

The study emphasized the complex interaction between the GH and the thyroid axes in patients with GHPA and highlighted the potential effect of glycemic status and tumor volume on thyroid function.

Thyroid Hormone Receptor-β Agonists in NAFLD Therapy: Possibilities and Challenges

Nonalcoholic fatty liver disease (NAFLD) is a progressive metabolic liver disease with an unknown pathogenesis and no FDA-approved drug treatment to date. Hypothyroidism has been identified as a risk factor for NAFLD as thyroxine is required for regulating metabolism in adults. Thyroxine has been shown to reduce fat in the livers of murine models with experimentally induced NAFLD. The use of synthetic thyroxine has been shown to increase lipid metabolism leading to weight loss; however, thyroxine has also been shown to cause many side effects, especially in the heart. Overcoming these cardiac side effects involves designing agonists specific to one of the 2 gene subtypes for the thyroid hormone (TH) receptor (TR), TRβ. While the other TH receptor subtype, TRα, is mainly expressed in the heart and is responsible for thyroxine's cardiac function, TRβ is mainly expressed in the liver and is involved in liver function. Using TRβ-specific agonists to treat NAFLD can prevent cardiac and other adverse side effects. Several TRβ-specific agonists have shown positive therapeutic effects in NAFLD animal models and have entered clinical trials. We seek to provide a comprehensive updated reference of TRβ-specific agonists in this review and explore the future therapeutic potential of TRβ-specific activation in the treatment of NAFLD.

Correlation between thyroid function, sensitivity to thyroid hormones and metabolic dysfunction-associated fatty liver disease in euthyroid subjects with newly diagnosed type 2 diabetes

PURPOSE

To estimate the prevalence of metabolic dysfunction-associated fatty liver disease (MAFLD) and to evaluate the associations between thyroid parameters, MAFLD and liver fibrosis in euthyroid patients with newly diagnosed type 2 diabetes mellitus (T2DM).

METHODS

Overall, 776 patients with newly diagnosed T2DM and 120 subjects without diabetes were included. All the participants were euthyroid, and were categorized as non-MAFLD and MAFLD. Demographic information, biochemical parameters, and serum thyroid hormones were collected. The thyroid hormone sensitivity indices were calculated. MAFLD was defined according to abdominal ultrasound and clinical manifestations. Noninvasive fibrosis indices were calculated to identify advanced liver fibrosis.

RESULTS

The prevalence of MAFLD was significantly higher in patients with T2DM than in subjects without diabetes. Levels of free triiodothyronine (FT3) and FT3 to free thyroxine (FT4) ratio were significantly higher in subjects with MAFLD. In patients with T2DM, levels of thyroid stimulating hormone (TSH), Thyroid feedback quantile-based index (TFQI_FT3) calculated using FT3 and TSH, thyrotroph T3 resistance index (TT3RI) and thyrotroph T4 resistance index (TT4RI) were significantly higher in subjects with MAFLD. The prevalence of MAFLD increased with the rise of FT3, FT3/FT4, TSH, and sensitivity to thyroid hormone indices (TFQI_FT3, TT3RI, and TT4RI). But significant correlations were not found between thyroid hormones, sensitivity to thyroid hormones and MAFLD, after adjustment for BMI and HOMA-IR. The incidence of advanced fibrosis tended to increase as the rise of TSH and sensitivity to thyroid hormone indices (TFQI_FT3, TT3RI, TT4RI, and TSHI).

CONCLUSION

MAFLD was prevalent in euthyroid patients with newly diagnosed T2DM. Higher normal FT3, TSH and impaired sensitivity to thyroid hormones are associated with increased incidence of MAFLD, being dependent on other metabolic factors.

Nonalcoholic Steatohepatitis in Children

Nonalcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease in children. Although environmental factors are major contributors to early onset, children have both shared and unique genetic risk alleles as compared with adults with NAFLD. Treatment relies on reducing environmental risk factors, but many children have persistent diseases. No medications are approved specifically for the treatment of NAFLD, but some anti-obesity or diabetes treatments may be beneficial. Pediatric NAFLD increases the risk of diabetes and other cardiovascular risk factors. Long-term prospective studies are needed to determine the long-term risk of hepatic and non-hepatic morbidity and mortality in adulthood.

Mediating effect analysis of visceral adiposity index on free triiodothyronine to free thyroxine ratio and non-alcoholic fatty liver disease in euthyroid population

BACKGROUND

The association between free triiodothyronine/free thyroxine (FT3/FT4) and non-alcoholic fatty liver disease (NAFLD) in euthyroid subjects is unclear. In addition, few studies have explored whether VAI mediates the association between FT3/FT4 ratio and NAFLD in the euthyroid population. We aimed to analyze the mediating effect of VAI on the FT3/FT4 ratio and NAFLD risk in the euthyroid population.

METHODS

This cross-sectional study included 7 946 annual health examinees from the Health Examination Center, Hebei General Hospital, from January to December 2020. The basic information and biochemical parameters, as well as calculated FT3/FT4 ratio and VAI were collected. NAFLD was diagnosed according to abdominal ultrasonography. The fibrosis score for NAFLD positive subjects (NFS) was calculated to reflect the extent of liver fibrosis. The risk of NAFLD was analyzed by quartiles of FT3/FT4 ratio (Q1-Q4 quartiles) and VAI (V1-V4 quartiles), respectively. Pearson correlation analysis was performed to investigate the correlation between FT3/FT4 ratio and VAI. Multivariate logistic regression analysis was applied to analyze the effect of FT3/FT4 ratio and VAI on NAFLD and NFS status. Bootstrap was conducted to explore whether VAI mediated the association between FT3/FT4 ratio and NAFLD.

RESULTS

Of the 7 946 participants, 2 810 (35.36%) had NAFLD and 5 136 (64.64%) did not. Pearson correlation analysis indicated that FT3/FT4 ratio was positively associated with VAI (P<0.05). Multivariate logistic regression analysis indicated that compared to the Q1 group, the risk of NAFLD significantly increased in Q3 group [OR=1.255, 95%CI (1.011, 1.559)] and Q4 group [OR=1.553, 95%CI (1.252, 1.926)](P<0.05). Compared to the V1 group, the risk of NAFLD notably increased in V2 group [OR=1.584, 95%CI (1.205, 2.083)], V3 group [OR=2.386, 95%CI (1.778, 3.202)] and V4 group [OR=4.104, 95%CI (2.835, 5.939)] (P<0.01). There was no relevance between FT3/FT4 ratio, VAI and NFS status. Mediating effect analysis showed that FT3/FT4 ratio significantly directly influenced NAFLD prevalence [β=3.7029, 95%CI (2.9583, 4.4474)], and VAI partly mediated the indirect effect of the FT3/FT4 ratio on NAFLD prevalence [β=2.7649, 95%CI (2.2347, 3.3466)], and the mediating effect accounted for 42.75% of the total effects.

CONCLUSION

Both FT3/FT4 ratio and VAI were predictors of NAFLD, and VAI partly mediated the indirect effect of the FT3/FT4 ratio on NAFLD prevalence in the euthyroid population.

Unraveling the Role of Hypothyroidism in Non-alcoholic Fatty Liver Disease Pathogenesis: Correlations, Conflicts, and the Current Stand

Non-alcoholic fatty liver disease (NAFLD) has become one of the most common causes of chronic liver diseases globally. Because thyroid hormones play a crucial role in lipid metabolism, thyroid dysfunction has been implicated in NAFLD pathogenesis in the past decade, with hypothyroidism-induced NAFLD being regarded as a distinct disease entity. However, there has been no common consensus yet, and several studies have found contradictory results. Hence, we conducted this systematic review to represent the current view on the role of hypothyroidism (HT) and individual thyroid function parameters such as thyroid-stimulating hormone (TSH), thyroxine (T4), triiodothyronine (T3), thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) in NAFLD pathogenesis. We searched PubMed, PubMed Central, and Semantic Scholar databases from inception until January 2021 to identify relevant observational (case-control, cross-sectional, and longitudinal) studies. A total of 699 articles were recognized through our database search. After applying the eligibility criteria and performing quality assessment, 10 studies involving 42,227 participants were included in the final systematic review. Each of these studies assessed different thyroid function parameters, and NAFLD was found to be associated with HT in two studies, elevated TSH in three studies, suppressed T4 in three studies, elevated T3 in one study, and elevated TPOAb in one study. There was also a wide heterogeneity in HT definition, study population characteristics, and study design among these studies, making a direct comparison difficult. Because the recognition of HT-induced NAFLD has possible diagnostic, therapeutic, and prognostic implications, we recommend that comprehensive, long-term prospective studies be carried out to determine if HT or thyroid function parameters are causally associated with NAFLD.

Free Triiodothyronine Is Independently Associated with Nonalcoholic Fatty Liver Disease in Hospitalized Type 2 Diabetes Mellitus Patients

OBJECTIVE

Free triiodothyronine (FT3) is an independent risk factor for nonalcoholic fatty liver disease (NAFLD) in patients with euthyroid. However, whether FT3 has an independent effect on NAFLD in a population of type 2 diabetes remains unknown. The purpose of this study was to identify the potential role of FT3 in NAFLD with T2DM.

DESIGN

A cross-sectional study. Patient. A total of 859 T2DM patients who met the inclusion criteria were included. There were 506 T2DM patients without NAFLD and 353 T2DM patients with NAFLD.

METHODS

The independent samples t-test or Wilcoxon rank sum test were used for continuous variables of different distribution types, while the chi-square test was used for categorical variables. Pearson correlation analysis and linear regression were used to analyze the correlation between FT3 and clinical measurements and biochemical indicators. Multivariate logistic regression analysis was used to determine independent predictors.

RESULTS

Patients with NAFLD had higher BMI, SBP, and DBP, longer duration of T2DM, and higher islet function index, blood glucose index, liver function index, renal function index, blood lipid index, and FT3. We also found that FT3 was affected by other five indicators, including ALT, CR, GGT, TC, and LDL-C only in the NAFLD group but not in the non-NAFLD group. FT3 was significantly associated with NAFLD in T2DM patients, and the prevalence of NAFLD increased gradually from the lowest FT3 tertile to the highest FT3 tertile (P for trend < 0.001).

CONCLUSION

FT3 is independently associated with NAFLD in hospitalized T2DM patients after rigorous adjustment for various metabolic parameters.

Sensitivity to Thyroid Hormone Indices Are Closely Associated With NAFLD

BACKGROUND

Previous studies on the association between thyroid function and non-alcoholic fatty liver disease (NAFLD) have contradicted. Acquired resistance to thyroid hormone theory might provide a reasonable explanation for these contradictions. We aimed to analyze the association between sensitivity to thyroid hormone indices with NAFLD.

METHODS

A total of 4,610 individuals from the health medical center of the First Hospital of China Medical University were included in this study. The previously used thyroid feedback quantile-based index (TFQI_FT4) was calculated. Also, we substituted free triiodothyronine (FT₃) into the TFQI formulas to get the TFQI_FT3 index. NAFLD was defined using abdominal ultrasound.

RESULTS

Study results showed that FT₃/FT₄ and TFQI_FT3 were positively correlated with the triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels (P<0.05) and negatively correlated with high-density lipoprotein cholesterol (HDL-C) level (P<0.05). In contrast, TFQI_FT4 was positively correlated with HDL-C level (P < 0.05). After adjustment for multiple confounders, FT₃, FT₃/FT₄, and TFQI_FT3 were positively associated with the risks of dyslipidemia and NAFLD (P < 0.05). TFQI_FT3 and FT₃/FT₄ performed better than TFQI_FT4 on ROC analyses for NAFLD prediction, although the diagnostic sensitivity and specificity at the optimal cut-points were low. However, no association was observed between TFQI_FT4 with the risks of dyslipidemia and NAFLD.

CONCLUSION

TFQI_FT3 and FT₃/FT₄ can be used as new indicators for predicting dyslipidemia and NAFLD, although with low sensitivity and specificity at the optimal cut-points, while TFQI_FT4 has insufficient evidence in predicting dyslipidemia and NAFLD.

Development and validation of a noninvasive clinical scoring system to predict significant fibrosis in patients with nonalcoholic fatty liver disease

BACKGROUND

The aims of this study were to identify risk factors for significant fibrosis (SF) by assessing physical and laboratory parameters and develop and validate a clinical score and nomogram for the prediction of SF in patients with nonalcoholic fatty liver disease (NAFLD).

METHODS

This retrospective study included 225 patients with histologically confirmed NAFLD who were divided into two cohorts using 10-fold cross validation for model training and validation. The clinical score and nomogram were used to predict the NAFLD outcome.

RESULTS

The model for predicting SF (stage ≥ 2) including the free T4/free T3 ratio, low-density lipoprotein cholesterol, homeostatic model assessment for insulin resistance (HOMA-IR), percentage of appendicular skeletal muscle mass and aspartate aminotransferase (AST) level in the training and validation cohorts yielded an area under the receiver operator characteristic curve (AUROC) of 0.79 and 0.78, respectively. The AUROC of the combined clinical score for the prediction of SF was 0.82 (95% CI, 0.75-0.89) at a cutoff value of 3 points, with a sensitivity (SE) of 77.19%, specificity (SP) of 82.88%, positive predictive value (PPV) of 63.77%, and negative predictive value (NPV) of 90.30%. The nomogram had good performance in quantitatively predicting the risk probability of SF.

CONCLUSION

Our study showed that a noninvasive clinical scoring system using easily available physical and laboratory variables can identify patients with NAFLD with or without SF with a high degree of accuracy. Application of this system may decrease the need for staging liver biopsy specimens and allow early identification and intervention in these high-risk patients.

Effect of TSH on Non-Alcoholic Fatty Liver Disease (NAFLD) independent of obesity in children of predominantly Hispanic/Latino ancestry by causal mediation analysis

Background

Nonalcoholic Fatty Liver Disease (NAFLD) is a common co-morbidity of obesity. Elevated TSH levels (eTSH), also associated with obesity, may contribute to the dysmetabolic state that predisposes to NAFLD.

Objective

To assess the relationship between TSH levels and NAFLD in children with biopsy-proven NAFLD compared to controls.

Design and methods

In this retrospective study of children with biopsy-proven NAFLD and age-matched controls, the association of eTSH with NAFLD was investigated and the role of TSH as a mediator between obesity and NAFLD was assessed.

Results

Sixty-six cases and 4067 controls (69.7 vs 59% Hispanic/Latino ancestry, p = 0.1) of the same age range seen in the same time duration at an urban Children’s Hospital were studied. Children with NAFLD were more likely to be male (74.6 vs 39.4%, p < 0.001), have higher modified BMI-z scores (median 2.4 (IQR 1.7) vs 1.9 (IQR 1.7), p < 0.001), and abnormal metabolic parameters (TSH, ALT, HDL-C, non-HDL-C, and TG). Multivariate analyses controlling for age, sex and severity of obesity showed significant association between the 4^th quartile of TSH and NAFLD. Causal mediation analysis demonstrates that TSH mediates 33.8% of the effect of modified BMI-z score on NAFLD. This comprises of 16.0% (OR = 1.1, p = 0.002) caused by the indirect effect of TSH and its interaction with modified BMI-z, and 17.7% (OR = 1.1, p = 0.05) as an autonomous effect of TSH on NAFLD. Overall, 33.8% of the effect can be eliminated by removing the mediator, TSH (p = 0.001).

Conclusions

The association of eTSH and biopsy-proven NAFLD is demonstrated in children of Hispanic/Latino ancestry. Further, a causal mediation analysis implicates an effect of TSH on NAFLD, independent of obesity.

Effects of thyroid diseases on pregnancy outcomes

The current study aimed to analyze the effects of thyroid diseases on pregnancy outcomes and investigate the effects of levothyroxine (L-T4) tablets in the treatment of hypothyroidism. The current study determined the prevalence of thyroid diseases using two diagnostic criteria, the prevalence of thyroid diseases among pregnant women recruited in 2010 and 2014 were initially determined by the 2011 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum (2011 ATA Guidelines). Subjects were categorized into six groups: Normal, hypothyroxinemia, hypothyroidism, subclinical hypothyroidism (SCH), hyperthyroidism and subclinical hyperthyroidism. L-T4 was administered in the thyroid-insufficient groups and the prevalence rates of these categories were obtained using the diagnostic criteria from the 2011 ATA Guidelines and the 2012 Chinese Guidelines for the Diagnosis and Treatment of Thyroid Disease During Pregnancy and Postpartum (2012 Chinese Guidelines). The results of the current study demonstrated that the screening of thyroid function was significantly increased in 2014 (thyroid dysfunction rate, 82.4% vs. 29.1%; P<0.001). Hypothyroxinemia, hypothyroidism, SCH, hyperthyroidism and subclinical hyperthyroidism increased the likelihood of certain adverse outcomes and complications. L-T4 decreased the odds of gestational hypertension, premature birth and low birth weight or very low birth weight in the hypothyroidism group. A statistically significant difference was identified between thyroid disease incidences as determined by the 2011 ATA Guidelines 2012 Chinese Guidelines. In conclusion, abnormal thyroid levels increased the odds of adverse pregnancy outcomes, L-T4 administration improved pregnancy outcomes and the 2012 Chinese Guidelines may provide a better reference for Chinese pregnant women with subclinical hyperthyroidism.

Reduced expression of thyroid hormone receptor β in human nonalcoholic steatohepatitis

Hepatic thyroid hormone signaling has an important role in the development and progression of nonalcoholic steatohepatitis (NASH). While the systemic levels of thyroid hormone might remain stable, there is evidence that the intracellular signaling machinery consisting of transporters, deiodinases and receptors could be altered in NASH. However, clinical material from human liver biopsies of individuals with NASH has not been studied to date. In a cross-sectional study, we analyzed 85 liver biopsies from patients with different stages of NASH that underwent bariatric surgery. Using qPCR, we analyzed gene expression of thyroid hormone transporters NTCP (SLC10A1), MCT8 (SLC16A2) and OATP1C1 (SLCO1C1), thyroid hormone receptor α and β (THRA and THRB) and deiodinase type I, II and III (DIO1, DIO2, DIO3). The expression was correlated with serum TSH, triglyceride, HbA1c and NASH score and corrected for age or gender if required. While DIO2, DIO3 and SLCO1C1 were not expressed in human liver, we observed a significant negative correlation of THRB and DIO1 with age, and SLC16A2 with gender. THRB expression was also negatively associated with serum triglyceride levels and HbA1c. More importantly, its expression was inversely correlated with NASH score and further declined with age. Our data provide unique insight into the mRNA expression of thyroid hormone transporters, deiodinases and receptors in the human liver. The findings allow important conclusions on the intrahepatic mechanisms governing thyroid hormone action, indicating a possible tissue resistance to the circulating hormone in NASH, which becomes more prominent in advanced age.

Association of non-alcoholic fatty liver disease with thyroid function: A systematic review and meta-analysis

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases. The relationship of NAFLD with thyroid function parameters and hypothyroidism remains controversial.

AIM

To clarify the effect of thyroid function parameters and hypothyroidism on the development of NAFLD and progression to nonalcoholic steatohepatitis (NASH).

METHODS

PubMed, EMBASE, and Cochrane library databases were searched. Study quality was assessed. Weighted mean difference (WMD) and odds ratio (OR) with 95% confidence interval (CI) were calculated.

RESULTS

Twenty six studies involving 61,548 participants were eligible, most of which were of high quality. NAFLD/NASH patients had significantly higher TSH levels than controls in adults (NAFLD versus health: WMD = 0.105, 95%CI = 0.012-0.197; NAFLD versus euthyroidism: WMD = 0.100, 95%CI = 0.005-0.194; NASH versus NAFLD: WMD = 0.540, 95%CI = 0.136-0.944) and children/adolescents (NAFLD versus lean controls: WMD = 1.039, 95%CI = 0.104-1.973; NAFLD versus overweight/obese controls: WMD = 0.485, 95%CI = 0.267-.703). Unclassified hypothyroidism was positively associated with the risk of NAFLD/NASH in adults (NAFLD versus health: OR = 1.605, 95%CI = 1.180-2.183; NASH versus NAFLD: OR = 2.317, 95%CI = 1.425-3.768) and children/adolescents (NAFLD versus overweight/obese controls: OR = 2.015, 95%CI = 1.246-3.258). However, the statistical results were inconsistent among the subgroup meta-analyses of subclinical and overt hypothyroidism. Association of NAFLD with FT3 and FT4 levels was heterogeneous among population.

CONCLUSION

TSH level may be an important risk factor for the development and progression of NAFLD, independent of thyroid hormones.

Thyroid Function in Korean Adolescents with Obesity: Results from the Korea National Health and Nutrition Examination Survey VI (2013-2015)

PURPOSE

In this study, we investigated the status of thyroid function and its association with metabolic risk factors in Korean adolescents.

METHODS

Among 2679 subjects aged 10-19 years who participated in the Korea National Health and Nutrition Examination Survey VI (2013-2015), 1067 adolescents (M = 559, F = 508) with available data on free T4 (FT4) and thyroid-stimulating hormone (TSH) were included. Study participants were classified into normal weight [body mass index (BMI) below 85th percentile, 80.7%], overweight (85th ≤ BMI< 95th percentile, 8.7%), and obesity (BMI ≥ 95th percentile, 10.6%).

RESULTS

With increasing levels of BMI category, the means of TSH increased (2.73 ± 0.06, 2.77 ± 0.02, and 3.24 ± 0.22 mIU/L, P = 0.031) and FT4 decreased (1.30 ± 0.01, 1.26 ± 0.02, and 1.25 ± 0.02 ng/mL, P = 0.001). Positive linear associations were observed between TSH and BMI z-score (P = 0.031), waist circumference (P = 0.013), waist-height ratio (P = 0.002), systolic blood pressure (P = 0.001), total cholesterol (P = 0.008), and triglyceride (P = 0.002) after adjusting for age and sex. With per-unit increase in TSH, the odds ratios of having abdominal obesity (OR = 1.18, 95% CI, 1.01-1.38) and triglyceride ≥ 150 mg/dL (OR = 1.18, 95% CI, 1.04-1.34) were significantly increased after adjusting for age, sex, and BMI.

CONCLUSIONS

In adolescents with obesity, TSH was higher and FT4 was lower than in adolescents with normal weight. Hyperthyrotropinemia was associated with abnormal metabolic risk factors including abdominal obesity and elevated triglyceride.

Thyroid Hormone Regulation and Insulin Resistance: Insights From Animals Naturally Adapted to Fasting

The contribution of thyroidal status in insulin signaling and glucose homeostasis has been implicated as a potential pathophysiological factor in humans, but the specific mechanisms remain largely elusive. Fasting induces changes in both thyroid hormone secretion and insulin signaling. Here, we explore how mammals that undergo natural, prolonged bouts of fasting provide unique insight into evolved physiological adaptations that allow them to tolerate such conditions despite intermittent states of reversible insulin resistance. Such insights from nature may provide clues to better understand the basis of thyroidal involvement in insulin dysregulation in humans.

Thyroid dysfunction and hepatic steatosis in overweight children and adolescents

BACKGROUND

Overt or subclinical hypothyroidism is a common finding in adult populations affected by non-alcoholic fatty liver disease (NAFLD). Currently, there are only sparse data available on the association of thyroid dysfunction and NAFLD in obese children and adolescents.

OBJECTIVE

The study aims to investigate the association of thyroid function test values with NAFLD and metabolic risk factors in a population of obese children and adolescents.

METHODS

A total of 332 overweight and obese children and adolescents (170 girls) aged between 10 and 19 years were analysed. Subjects underwent ultrasound examination of the liver. Thyroid function was evaluated by laboratory determination of thyroid-stimulating hormone (TSH), total triiodothyronine (T3) and total thyroxine levels. All included subjects were either euthyroid or had subclinical hypothyroidism (TSH > 4 μU mL^-1 , normal thyroxine). Further metabolic profiling included the determination of lipid status, insulin and liver function tests. Anthropometric parameters body mass index, waist and hip circumference were documented.

RESULTS

The prevalence of hepatic steatosis was 29.8%. Subjects with NAFLD had significantly higher TSH levels than those without (p = 0.0007). After dividing TSH values into quartiles, both univariate and multivariate analyses (adjusted for age, body mass index-standard deviation scores and stage of puberty) showed a significant association with hepatic steatosis (p < 0.05).

CONCLUSION

Taking possible variables into consideration, our results show that there is a significant association between hepatic steatosis and the TSH levels in obese children and adolescents. Mild thyroid dysfunction may therefore have a role in determining an unfavourable metabolic profile in obese children and adolescents.

Relationship between Hypothyroidism and Non-Alcoholic Fatty Liver Disease: A Systematic Review and Meta-analysis

BACKGROUND

Previous studies propose that hypothyroidism might play a crucial role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD), but findings from published studies on the relationship between hypothyroidism and NAFLD are still controversial. Our study aimed to make a comprehensive evaluation of the relationship between hypothyroidism and NAFLD through a meta-analysis.

METHODS

PubMed, China Dissertation Database, and EMBASE databases were searched to find observational studies assessing the relationship between hypothyroidism and NAFLD. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to evaluate the strength of the relationship between hypothyroidism and NAFLD through meta-analysis.

RESULTS

Thirteen articles were ultimately included in our meta-analysis. Meta-analysis of the 13 studies found a high correlation between hypothyroidism and NAFLD (OR = 1.52, 95% CI 1.24-1.87, P < 0.001). Meta-analysis of 9 studies providing adjusted ORs found that hypothyroidism was independently correlated with NAFLD (OR = 1.72, 95% CI 1.32-2.23, P < 0.001). Subgroup analysis found that both overt hypothyroidism and subclinical hypothyroidism were significantly correlated with NAFLD, and the pooled ORs were 1.70 (95% CI 1.23-2.36, P = 0.002) and 1.40 (95% CI 1.10-1.77, P = 0.006), respectively. Besides, meta-analysis of studies providing adjusted ORs also found that both overt hypothyroidism and subclinical hypothyroidism were independently correlated with NAFLD, and the pooled ORs were 1.81 (95% CI 1.30-2.52, P < 0.001) and 1.63 (95% CI 1.19-2.24, P = 0.002), respectively.

CONCLUSION

The meta-analysis provides strong epidemiological evidence for the relationship between hypothyroidism and NAFLD. Both individuals with subclinical and overt hypothyroidism are at higher risk for NAFLD than euthyroid subjects.

FT3/FT4 ratio predicts non-alcoholic fatty liver disease independent of metabolic parameters in patients with euthyroidism and hypothyroidism

OBJECTIVE

This study was performed to evaluate the effects of metabolic parameters and thyroid dysfunction on the development of non-alcoholic fatty liver disease (NAFLD).

METHODS

The current study evaluated a total of 115 patients, 75 female and 40 male. Physical examination and anthropometric measurements were applied to all participants. Hypothyroidism was considered at a thyroid stimulating hormone level ≥ 4.1 mIU/L. Patients with euthyroidism and patients with hypothyroidism were compared. Abdominal ultrasonography was used to diagnose non-alcoholic fatty liver disease. The participants were further compared with regard to the presence of non-alcoholic fatty liver disease. Logistic regression modeling was performed to identify the relationship between non-alcoholic fatty liver disease and independent variables, such as metabolic parameters and insulin resistance.

RESULTS

Non-alcoholic fatty liver disease was identified in 69 patients. The mean waist circumference, body mass index, fasting plasma insulin, HOMA-IR (p<0.001) and FT3/FT4 ratio (p=0.01) values were significantly higher in the patients with NAFLD compared to those without it. Multivariate regression analysis revealed that FT3/FT4 ratio, waist circumference and insulin resistance were independent risk factors for non-alcoholic fatty liver disease.

CONCLUSION

Insulin resistance, enlarged waist circumference, elevated body mass index, higher FT3/FT4 ratio and hypertriglyceridemia are independent risk factors for NADLF, whereas hypothyroidism is not directly related to the condition.

Indices of Central and Peripheral Obesity; Anthropometric Measurements and Laboratory Parameters of Metabolic Syndrome and Thyroid Function

BACKGROUND

Metabolic syndrome (MetS) and obesity are serious health problems in the World, including Turkey. Contemporary studies have suggested a meaningful association between insulin resistance (IR), MetS parameters, and thyroid function tests.

AIMS

We aimed to elucidate the impact of fat distribution on the anthropometric and laboratory parameters, especially indices of MetS, IR and thyroid function, in obese women.

STUDY DESIGN

Cross-sectional study.

METHODS

Anthropometric measurements of all participants and biochemical tests in their serum samples were performed.

RESULTS

Weight, waist circumference (WC), body mass index (BMI), and other parameters of fat distribution were significantly increased in all obese compared to control subjects; but there was no significant difference between central and peripheral obese groups. The central obese group had significantly higher insulin levels, components of MetS, the ratio free triiodothyronine (fT3) to free thyroxin fT4, and fT4 than those of peripheral obese and control groups.

CONCLUSION

Elevated triglyceride, glucose and insulin levels may be associated with increased IR, which in turn is related to MetS. Body fat composition may affect thyroid tests in the obese; the changes in fT3/fT4 could be the consequence of fat distribution.