Vitamin D levels and liver histological alterations in children with nonalcoholic fatty liver disease

Objective: To investigate the association between plasma vitamin D (VD) levels and histological liver damage in children with nonalcoholic fatty liver disease (NAFLD). Subjects and methods: In this cross-sectional study, carried out in a tertiary care center for obesity, 73 consecutive overweight and obese children with persistently elevated serum aminotransferase levels and diffusely hyperechogenic liver on ultrasonography were selected for liver biopsy. Nonalcoholic steatohepatitis (NASH) and fibrosis were histologically diagnosed using NAFLD Clinical Research Network (CRN) criteria. The plasma levels of 25-OH-VD were measured by HPLC. Bone mineral density (BMD) of lumbar spine was evaluated by dual-energy X-ray absorptiometry. Multiple linear regression analysis was used to evaluate the association between 25-OH-VD levels and the predictors of interest after correction for age, gender, waist circumference, BMI, and other potential confounders. Results: The children (64% males) were aged 8-18 years, and their median BMI was 2.45 SDS. Both parathyroid hormone levels and BMD were within the normal range. All cases of fibrosis were detected in children with NASH. On multivariable linear regression with correction for age, gender, and BMI, 25-OH-VD levels were found to be 9 (95% CI 12-6) ng/ml lower in children with NASH than in those without NASH (P < 0.001) and 9 (12-6) ng/ml lower in children with stage 1 fibrosis than in those with stage 0 fibrosis and 9 (13-6) ng/ml lower in children with stage 2 than in those with stage 0 fibrosis (P < 0.001 for both). Conclusion: VD levels are inversely associated with NASH and fibrosis in children with NAFLD.