The predictive role of parathyroid hormone for non-alcoholic fatty liver disease based on invasive and non-invasive findings in candidates of bariatric surgery

High parathyroid hormone level as a marker of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis: A systematic review and meta-analysis

BACKGROUND AND AIMS

Studies have suggested that high parathyroid hormone (PTH) was associated with non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH), although the results from existing studies are inconsistent. Using systematic review and meta-analysis, we aimed to determine the association of PTH with NAFLD and NASH.

METHODS

Potentially eligible studies were identified from Embase and Medline databases from using search strategy consisting of terms for "NAFLD/NASH", and "PTH". Eligible study must consist of one group of patients with NAFLD/NASH and another group without NAFLD/NASH. The study must provide mean ± SD PTH in both groups. We extracted such data to calculate mean difference (MD). Pooled MD was then calculated by combining MDs of each study using random-effects model. Funnel plot was used to assess for the presence of publication bias.

RESULTS

A total of 388 articles were identified. After systematic review, 12 studies fulfilled the eligibility criteria and were included into the meta-analysis. The meta-analysis of 10 studies revealed the significant association between high PTH and NAFLD, with the pooled MD of 5.479 (95%CI 0.947-10.011, I2 82.4%). The funnel plot was symmetric and did not suggest publication bias. The meta-analysis of 4 studies revealed the non-significant association between high PTH and NASH, with the pooled MD of 11.955 (95%CI -4.703 - 28.614, I2 81.0%).

CONCLUSIONS

High PTH level is significantly associated with NAFLD and can be used as a marker of NAFLD. However, high PTH level is non-significantly associated with NASH. Further studies are needed to increase the sample size and eliminate the confounding factors.

Association between Thyroid Hormones and Non-alcoholic Fatty Liver Disease and Non-alcoholic Steatohepatitis in Obese Individuals Undergoing Bariatric Surgery

Background: Non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), and hepatic fibrosis have emerged as one of the leading causes of chronic liver disease. The prevalence of the NAFLD spectrum has increased, which can be attributed to the rise in obesity. As NAFLD can ultimately lead to liver cirrhosis, it is imperative to identify modifiable risk factors associated with its onset and progression to provide timely intervention to prevent potentially disastrous consequences. Considering the pivotal role of the endocrine axis in several metabolic pathways such as obesity and insulin resistance, thyroid hormones are crucial in the pathophysiology of NAFLD. The study is focused on the identification of an association between thyroid function and radiographic and histological parameters of NAFLD in patients with severe obesity. Methods: Ninety patients were recruited for this study and underwent initial assessments, including demographic profiles, anthropometric measurements, hepatic biopsy, and basic laboratory tests. Liver stiffness was evaluated using two-dimensional shear wave elastography (2D-SWE) at least 2 weeks before liver biopsy. Results: Among the 90 participants, 80% were women. The mean age was 38.5±11.1 years, and the mean body mass index (BMI) was 45.46±6.26 kg/m2. The mean levels of serum T3 and free T4 in patients with positive histology were not statistically significant compared with patients with negative histology. Furthermore, there was no statistical significance in the mean T3 and free T4 levels between patients diagnosed with hepatic steatosis or fibrosis (on ultrasonography and elastography) and those with negative hepatic imaging. Serum levels of thyroid-stimulating hormone (TSH) were negatively correlated with ultrasonography (P=0.007). Binary logistic regression analysis revealed that none of the thyroid hormones was a predictive factor for liver histology in both adjusted and crude models. Conclusion: The results from our analysis did not suggest an association between thyroid hormones and NAFLD, which is in line with several previously published studies. However, the authors note that there are published data that do propose a link between the two entities. Therefore, well-designed large-scale clinical studies are required to clarify this discrepancy.

The Predictive Role of Parathyroid Hormone for Nonalcoholic Fatty Liver Disease following Bariatric Surgery

Background

Morbid obesity is frequently complicated by chronic liver diseases, including nonalcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), and fibrosis. Parathyroid hormone (PTH) is found to be elevated in morbid obesity due to the defective hepatic metabolism of vitamin D. Bariatric surgery is performed to help patients with BMI>40 kg/m² to effectively lose weight, particularly in patients with obesity who are afflicted with complications such as NAFLD/NASH.

Objective

This study aimed to evaluate the PTH level as a predictor of hepatic function in individuals with morbid obesity who have undergone bariatric surgery.

Methods

Ninety subjects with morbid obesity referred for Roux en-Y gastric bypass surgery were recruited. After IRB approval, demographic profiles, anthropometric factors, liver biopsy, and laboratory tests were obtained. The two-dimensional shear wave elastography (2D-SWE) technique was applied to assess hepatic stiffness.

Results

A significant reduction occurred six months after bariatric surgery in the anthropometric indices (p < 0.001), hepatic elasticity (p=0.002), alanine aminotransferase (p < 0.001), serum alkaline phosphatase (p < 0.001), gamma-glutamyl transpeptidase (GGT) (p < 0.001), and nonalcoholic fatty liver disease fibrosis score (NFS) (p < 0.001). Serum PTH concentration was not predictive of postsurgical liver fibrosis and steatosis at six months but could predict weight loss success rate. No significant alteration in serum PTH levels was observed between presurgical vs. postsurgical time points.

Conclusion

A significant reduction was observed in the anthropometric parameters, liver enzymes, and hepatic elasticity after bariatric surgery. No significant effect was found on PTH levels.