Relationship Between Vitamin D, PTH and insulin resistance in the development of non-alcoholic fatty liver Disease (NAFLD)

Abstract

Introduction: Vitamin D plays an important role in the regulation of several genes associated with metabolic disorders. This study was designed to investigate the relationship between serum 25 (OH) D and parathyroid hormone (PTH) levels, and insulin resistance in patients with non-alcoholic fatty liver disease (NAFLD). Methods: A case-control study was carried out among patients with NAFLD (n= 80) as cases and age-matched subjects without NAFLD (n= 80) as controls. After 8-12 h of fasting, serum 25 (OH) D, insulin and PTH levels were assessed using Enzyme-Linked Immunosorbent Assay (ELISA) technique. Multivariate logistic regression model was applied to assess the relationship between vitamin D and PTH and insulin resistance in the development of NAFLD by adjusting for the confounders (sex, BMI and waist-to-hip ratio). Results: There was no significant difference in sunlight exposure between the two groups (p= 0.274). Patients with NAFLD had significantly lower serum 25(OH) D levels and higher PTH levels compared to subjects without NAFLD (p < 0.001). The association between NAFLD and low 25(OH) vitamin D levels was independent of confounders (adjusted OR: 8.78, CI 95%:1.71, 45.03). Homeostatic Model Assessment Insulin Resistance (HOMA-IR) as insulin resistance index was significantly high in the NAFLD group (adjusted OR: 1.80, CI 95%: 1.32, 2.47). Conclusion: Our findings showed that lower serum 25 (OH) D levels and higher HOMA indices were independently associated with increased odds of NAFLD and there was a direct but not significant relationship between PTH serum levels and the risk of NAFLD.