Correlation between the thyroid hormone levels and nonalcoholic fatty liver disease in type 2 diabetic patients with normal thyroid function

Thyroid function and hepatic fibrosis/cirrhosis: a two-sample Mendelian randomization study

Background

Evidence on the relationship between thyroid function and hepatic fibrosis/cirrhosis are still unclear, with inconsistent conclusions. This Mendelian randomization (MR) study aimed to investigate the potential causal association between thyroid function and hepatic fibrosis/cirrhosis in order to provide new insights for improving prevention and control strategies for this disease.

Methods

Genome-wide association study (GWAS) data on exposures, which included hyperthyroidism, hypothyroidism, and thyroid-stimulating hormone (TSH), were extracted from the MRC Integrative Epidemiology Unit (MRC-IEU) (https://gwas.mrcieu.ac.uk/), and GWAS data for outcomes, including hepatic fibrosis/cirrhosis and chitinase-3-like protein 1 (CHI3L1), were obtained from the FinnGen consortium (https://www.finngen.fi/fi). Inverse variance weighted (IVW), weighted median, and MR-Egger methods were utilized to examine the causal association between thyroid function and the risk of hepatic fibrosis/cirrhosis. Cochran's Q test was used to assess the heterogeneity of instrumental variables (IVs), while MR-PRESSO and leave-one-out analyses were conducted for sensitivity analysis.

Results

IVW estimates suggested that hypothyroidism had a potential causal association with higher odds of hepatic fibrosis/cirrhosis (OR = 1.247, 95% CI: 1.087-1.431). Leave-one-out results indicated that this potential causal relationship was relatively robust. In addition, we assessed the causal association between hypothyroidism and hepatic fibrosis/cirrhosis before and after removal of outliers with heterogeneity. After removing the outliers, the association was still significant (OR = 1.266, 95% CI: 1.082-1.482, P = 0.0046).

Conclusion

Patients with hypothyroidism may have a higher risk of hepatic fibrosis/cirrhosis, and this finding may provide some references for the early screening and prevention of the disease. However, further studies are needed to explore the specific mechanisms by which hypothyroidism influences hepatic fibrosis/cirrhosis.

Circulating Bilirubin Levels, but Not Their Genetic Determinants, Are Inversely Associated with Steatotic Liver Disease in Adolescents

Epidemiologic studies suggest that elevated plasma unconjugated bilirubin confer protection against steatotic liver disease (SLD) in adults. However, evidence supporting this protective role in adolescents remains limited. We aimed to assess the association between serum bilirubin levels and their genetic determinants in protecting against SLD in Chilean adolescents. We conducted a cross-sectional study with 704 adolescents aged 15.4 ± 1 years (52% girls) of the Chilean Growth and Obesity Cohort Study. Ultrasonography echogenicity was used to diagnose SLD. We measured Z-scores of body mass index (z-BMI), total bilirubin (TB), and the genetic determinants of bilirubin (including rs887829 genotypes of UGT1A1 and bilirubin polygenic scores). Multiple logistic regression models evaluated the associations between standardized TB and its genetic determinants with SLD. We found that 1-SD of standardized plasma TB was significantly associated with a 30% reduction in the likelihood of SLD after adjustment by sex, age, z-BMI, and ethnicity (OR = 0.7; 95% CI = 0.50-0.96; p = 0.03). No significant associations were found among the rs887829 genotypes, bilirubin polygenic scores, and SLD in logistic regression models adjusted by covariates. Increased circulating bilirubin levels are unlikely causally associated with protection against SLD, and the cross-sectional association could be due to unmeasured confounding.

Association of free triiodothyronine and total triiodothyronine with nonalcoholic fatty liver disease: from National Health and Nutrition Examination Survey and Mendelian randomization study

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with multiple factors, yet the relationship between NAFLD and thyroid-related biomarkers remains unclear. This study aims to elucidate this potential linkage.

METHODS

Utilizing data from the US National Health and Nutrition Examination Survey (NHANES), we explored the possible associations between thyroid-related biomarkers and NAFLD through multivariable logistic regression, subgroup analysis, and interaction tests. A bidirectional Mendelian randomization (MR) approach complemented by various sensitivity analyses was then employed to ascertain these relationships' causality.

RESULTS

Our NHANES analysis indicated significant associations between elevated levels of free triiodothyronine (FT3) [odds ratio (OR): 2.59, 95% confidence interval (CI): 1.50-4.49] and total triiodothyronine (TT3) (OR: 2.01, 95% CI: 1.27-3.18) with the prevalence of NAFLD. MR findings reinforced the causal relationship, demonstrating that NAFLD may elevate FT3 (β: 0.05, 95% CI: 0.01-0.09) and TT3 (β: 0.08, 95% CI: 0.02-0.14) levels. Additionally, thyroid-stimulating hormone (TSH) was confirmed as an independent risk factor for NAFLD (OR: 1.10, 95% CI: 1.04-1.18), with specific MR sensitivity analyses supporting the robustness of these results.

CONCLUSION

This study indicates potential elevations in FT3, TT3, and thyroglobulin levels associated with NAFLD, while also identifying TSH as a risk factor for NAFLD. These findings underscore the importance of routine thyroid function monitoring both in the general population and particularly in individuals with NAFLD.

Association between thyroid function and nonalcoholic fatty liver disease: a dose-response meta-analysis

Background

Thyroid hormones (THs) have been found that it is closely associated with the onset and progression of non-alcoholic fatty liver disease (NAFLD). However, the current study could not verify the intrinsic relationship between thyroid hormones and NAFLD, which requires further research.

Methods

The searches of studies reported both TH level in serum and NAFLD were performed in PubMed, Web of Science, Cochrane Library, and Embase databases. We combined an overall meta-analysis with a dose-response meta-analysis to assess the correlation and dose-response relationship between thyroid function levels and the risk of NAFLD.

Results

Overall, 10 studies were included with a total of 38,425 individuals. We found that the non-linear dose-response model showed that for every 1 ng/dL increase in FT4, the risk of NAFLD was reduced by 10.56% (p=0.003). The odds ratios (ORs) for NAFLD with high free triiodothyronine (FT3) exposure compared to those with low FT3 were 1.580 (95% CI 1.370 to 1.830, I2 = 0.0%, p<0.001) in the overall meta-analysis. The continuous variable meta-analysis indicated that individuals with high levels of TSH (SMD=1.32, 95% CI 0.660 to 1.970, p<0.001) had significantly higher levels of liver fibrosis than those with low levels.

Conclusions

Our findings only validate that there is a correlation between the occurrence of NAFLD and abnormal levels of THs, and it is expected that more observational studies will still be conducted in the future to further demonstrate the relationship between thyroid hormones and NAFLD.

Trial registration

Registered number in PROSPERO: CRD42023405052.

Impaired Sensitivity to Thyroid Hormones Is Associated With the Change of Abdominal Fat in Euthyroid Type 2 Diabetes Patients: A Retrospective Cohort Study

Background and Aims: This study is aimed at investigating the potential correlation of thyroid hormone sensitivity with visceral fat area (VFA), subcutaneous fat area (SFA), and body mass index (BMI) among euthyroid type 2 diabetes mellitus (T2DM) subjects. Methods: Thyroid hormone sensitivity indices were calculated by thyroid feedback quantile-based index (TFQI), TSH index (TSHI), thyrotropin thyroxine resistance index (TT4RI), and free thyroxine (fT4)/free triiodothyronine (fT3) ratio. These indices were then categorized into quartiles for analysis. The outcomes were the change rates in VFA, SFA, and BMI among the participants. Result: The present study included 921 patients, with a median follow-up of 2.2 years. In multivariate linear regression, when compared to the first quartile, SFA demonstrated a notable decline in the fourth quartile of TFQI, TSHI, and TT4RI (β coefficient = -5.78, -7.83, and - 6.84 cm2 per year), while it significantly increased in the fourth quartile of fT4/fT3 ratio (β coefficient = 6.13 cm2 per year). Similarly, in the fourth quartile of TFQI, TSHI, and TT4RI, VFA decreased significantly, evidenced by β coefficients of -5.14, -4.80, and -4.08 cm2 per year. Yet, among the quartiles of the fT4/fT3 ratio, no discernible trend in VFA was observed. There was no significant association between indices of thyroid hormone sensitivity and change in BMI. Conclusion: Impaired central sensitivity to thyroid hormones was significantly associated with the reduction of VFA and SFA, while impaired peripheral sensitivity was associated with an increase of SFA in euthyroid individuals with T2DM.

NAFLD Fibrosis Progression and Type 2 Diabetes: The Hepatic-Metabolic Interplay

The bidirectional relationship between type 2 diabetes and (non-alcoholic fatty liver disease) NAFLD is indicated by the higher prevalence and worse disease course of one condition in the presence of the other, but also by apparent beneficial effects observed in one, when the other is improved. This is partly explained by their belonging to a multisystemic disease that includes components of the metabolic syndrome and shared pathogenetic mechanisms. Throughout the progression of NAFLD to more advanced stages, complex systemic and local metabolic derangements are involved. During fibrogenesis, a significant metabolic reprogramming occurs in the hepatic stellate cells, hepatocytes, and immune cells, engaging carbohydrate and lipid pathways to support the high-energy-requiring processes. The natural history of NAFLD evolves in a variable and dynamic manner, probably due to the interaction of a variable number of modifiable (diet, physical exercise, microbiota composition, etc.) and non-modifiable (genetics, age, ethnicity, etc.) risk factors that may intervene concomitantly, or subsequently/intermittently in time. This may influence the risk (and rate) of fibrosis progression/regression. The recognition and control of the factors that determine a rapid progression of fibrosis (or its regression) are critical, as the fibrosis stages are associated with the risk of liver-related and all-cause mortality.

The Free Triiodothyronine, Gamma-Glutamyl Transpeptidase and Spontaneous Bacterial Peritonitis Index: A Novel Model for Predicting 1-Year Mortality in Patients with HBV-Related Hepatic Encephalopathy

Background and Aims

Hepatic encephalopathy (HE) is characterized by neuropsychiatric manifestations in patients with decompensated cirrhosis (DC) and/or liver failure. This study aimed to investigate the predictive value of thyroid hormone in patients with HE.

Methods

Patients with DC and HE were enrolled, and multivariate logistic analysis was conducted to analyze the risk factors for 1-year mortality.

Results

Among the 81 patients with HBV-related DC and HE, 9 (11.1%) died within 3 months, and 15 (18.5%) died within the first year. More patients with FT3 < 3.5pmol/L had ascites (33.3% vs 8.9%, P<0.01) and higher model for end-stage liver disease (MELD) (Z=3.669, P<0.01). Additionally, free triiodothyronine (FT3) levels were lower in the non-survivor group (P<0.01). FT3 exhibited a negative correlation with international normalized ratio and MELD (both P<0.05). Multivariate analysis revealed that FT3, gamma-glutamyl transpeptidase (GGT), and spontaneous bacterial peritonitis (SBP) were independent risk factors for 1-year mortality of HE. A new model incorporating FT3, GTT, and SBP demonstrated superiority to MELD based on the AUROC (0.9 and 0.752, P=0.04).

Conclusion

Low FT3, but not thyroid-stimulating hormone and free tetraiodothyronine, was identified as an independent risk factor for 1-year mortality in patients with DC and HE. The newly proposed prognostic model, which includes FT3, GTT, and SBP, holds significant predictive value.

Association of thyroid function with non-alcoholic fatty liver disease in recent-onset diabetes

BACKGROUND AND AIMS

Non-alcoholic fatty liver disease (NAFLD) has been linked to type 2 diabetes (T2D), but also to hypothyroidism. Nevertheless, the relationship between thyroid function and NAFLD in diabetes is less clear. This study investigated associations between free thyroxine (fT4) or thyroid-stimulating hormone (TSH) and NAFLD in recent-onset diabetes.

METHODS

Participants with recent-onset type 1 diabetes (T1D, n = 358), T2D (n = 596) or without diabetes (CON, n = 175) of the German Diabetes Study (GDS), a prospective longitudinal cohort study, underwent Botnia clamp tests and assessment of fT4, TSH, fatty liver index (FLI) and in a representative subcohort 1 H-magnetic resonance spectroscopy.

RESULTS

First, fT4 levels were similar between T1D and T2D (p = .55), but higher than in CON (T1D: p < .01; T2D: p < .001), while TSH concentrations were not different between all groups. Next, fT4 correlated negatively with FLI and positively with insulin sensitivity only in T2D (ß = -.110, p < .01; ß = .126, p < .05), specifically in males (ß = -.117, p < .05; ß = .162; p < .01) upon adjustments for age, sex and BMI. However, correlations between fT4 and FLI lost statistical significance after adjustment for insulin sensitivity (T2D: ß = -.021, p = 0.67; males with T2D: ß = -.033; p = .56). TSH was associated positively with FLI only in male T2D before (ß = .116, p < .05), but not after adjustments for age and BMI (ß = .052; p = .30).

CONCLUSIONS

Steatosis risk correlates with lower thyroid function in T2D, which is mediated by insulin resistance and body mass, specifically in men, whereas no such relationship is present in T1D.

Global prevalence of non-alcoholic fatty liver disease in type 2 diabetes mellitus: an updated systematic review and meta-analysis

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is the leading cause of chronic liver disease, with type 2 diabetes mellitus (T2DM) as a major predictor. Insulin resistance and chronic inflammation are key pathways in the pathogenesis of T2DM leading to NAFLD and vice versa, with the synergistic effect of NAFLD and T2DM increasing morbidity and mortality risks. This meta-analysis aims to quantify the prevalence of NAFLD and the prevalence of clinically significant and advanced fibrosis in people with T2DM.

METHODS

MEDLINE and Embase databases were searched from inception until 13 February 2023. The primary outcomes were the prevalence of NAFLD, non-alcoholic steatohepatitis (NASH) and fibrosis in people with T2DM. A generalised linear mixed model with Clopper-Pearson intervals was used for the analysis of proportions with sensitivity analysis conducted to explore heterogeneity between studies.

RESULTS

156 studies met the inclusion criteria, and a pooled analysis of 1 832 125 patients determined that the prevalence rates of NAFLD and NASH in T2DM were 65.04% (95% CI 61.79% to 68.15%, I2=99.90%) and 31.55% (95% CI 17.12% to 50.70%, I2=97.70%), respectively. 35.54% (95% CI 19.56% to 55.56%, I2=100.00%) of individuals with T2DM with NAFLD had clinically significant fibrosis (F2-F4), while 14.95% (95% CI 11.03% to 19.95%, I2=99.00%) had advanced fibrosis (F3-F4).

CONCLUSION

This study determined a high prevalence of NAFLD, NASH and fibrosis in people with T2DM. Increased efforts are required to prevent T2DM to combat the rising burden of NAFLD.

PROSPERO REGISTRATION NUMBER

CRD42022360251.

The association between thyroid hormones and MAFLD is mediated by obesity and metabolic disorders and varies among MAFLD subtypes

BACKGROUND

Thyroid hormone (TH) disorders increased the risk of metabolic dysfunction-associated fatty liver disease (MAFLD).

AIM

To assess whether the association between TH and MAFLD is mediated via metabolic dysfunctions and varies among MAFLD subtypes (diabetes-MAFLD, overweight/obesity-MAFLD, metabolic disorders-MAFLD).

METHODS

A total of 18,427 participants (661 diabetes-MAFLD, 3,600 overweight/obesity-MAFLD, 691 metabolic disorder-MAFLD cases, 13,475 non-MAFLD controls) from a Chinese hospital were enrolled. Hepatic ultrasound measurements and thyroid function were assessed.

RESULTS

Overweight/obesity mediated the associations of MAFLD with triiodothyronine (T3), free triiodothyronine (FT3), free thyroxine (FT4), and the mediator accounted for 46.43%, 39.69%, and 42.68%, respectively. Metabolic disorder mediated the association of MAFLD with T3, FT3, FT4, thyroid stimulating hormone (TSH), and the mediator accounted for 36.57%, 23.19%, 34,65%, and 60.92%, respectively. Diabetes did not complementary mediate any association between TH and MAFLD. Elevated T3, FT3, TSH and decreased FT4 increased the risk of overweight/obesity-MAFLD, and the odds ratios were 1.59, 1.72, 1.18, and 0.60, respectively (Q4 vs.Q1, false discovery rate (FDR)<0.05). Elevated T3, FT3, and decreased FT4 increased the risk of metabolic disorder-MAFLD, and the odds ratios were 1.45, 1.33, and 0.52, respectively (Q4 vs.Q1, FDR<0.05). No significant association between TH and diabetes-MAFLD was detected.

CONCLUSION

The association between TH and MAFLD is mediated by overweight/obesity and metabolic disorders and varies among MAFLD subtypes.

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.