The Association between Vitamin D Deficiency and Hepatosteatosis in Children and Adolescents with Obesity

Abstract

Introduction: Increasingly, research groups have been studying the association of serum vitamin D and metabolic health indicators, especially in patients with obesity. We compared the serum 25-hydroxyvitamin D (25(OH)D) concentrations in children and adolescents who had obesity and hepatosteatosis with children and adolescents who had obesity without hepatosteatosis and investigated the relationship between serum 25(OH)D concentrations and severity of hepatosteatosis. We also aimed to assess the effect of vitamin D treatment after 6 months on hepatosteatosis and liver biochemistry. Methods: One hundred thirty-three patients with obesity (body mass index [BMI] >+2 standard deviations [SDs] for their age and gender) and vitamin D deficiency (serum 25(OH)D <12 ng/mL) were recruited. Anthropometric measurements, biochemical parameters (serum calcium, phosphate, alkaline phosphatase, parathyroid hormone, 25(OH)D, glucose and insulin concentrations), and ultrasonographic findings of hepatosteatosis were recorded before and 6 months after Vitamin D treatment. χ2, Student’s t tests, and multivariate analysis were performed. Results: Grade 1, 2, and 3 hepatosteatosis at baseline was present in 51 (38.4%), 43 (32.3%), and 10 (7.5%) subjects, respectively. Mean (± SD) serum 25(OH)D concentrations were significantly lower in those with hepatosteatosis (8.4 ± 2.4 ng/mL) compared with those without hepatosteatosis (9.9 ± 2.4 ng/mL, p < 0.005). Multivariable logistic regression analysis showed serum 25(OH)D concentration was the independent predictor for hepatosteatosis (p < 0.005), whereas age, sex, weight SD, BMI SD, and homeostasis model of assessment (HOMA)-insulin resistance (IR) were not (p > 0.05). There was no significant difference in BMI SD, HOMA-IR, and liver enzymes between subjects with and without hepatosteatosis (p > 0.05). Despite improvement in serum 25(OH)D concentrations at 6 months post-treatment (34.7 ± 10.6 ng/mL vs. 8.7 ± 2.4 ng/mL; p < 0.0001), there was no significant difference in the proportion of patients with different severity of hepatosteatosis as compared to before treatment (p = 0.88). Conclusion: Serum 25(OH)D concentrations were lower in children and adolescents with obesity and hepatic steatosis as compared to those without hepatic steatosis, with an inverse association between the severity of hepatosteatosis and serum 25(OH)D concentrations. Vitamin D treatment in children and adolescents with obesity and hypovitaminosis D did not improve severity of hepatic steatosis on ultrasonography at 6 months.