Histologic Severity of Nonalcoholic Fatty Liver Disease Associates with Reduced Bone Mineral Density in Children.

ABSTRACT

BACKGROUND: Lower whole body bone mineral density (BMD) has been reported in children with nonalcoholic fatty liver disease (NAFLD), but potential mediators remain uncertain. AIMS: To assess BMD at multiple skeletal sites in children with confirmed NAFLD and controls with obesity, adjusting for known determinants of BMD, and examine potential mediators. METHODS: We assessed age-, sex-, and race-specific, and height-adjusted BMD z-scores of whole body, lumbar spine, hip, femoral neck and forearm by dual-energy-x-ray absorptiometry in 79 children, 8-19 years old 46 with biopsy-confirmed NAFLD [29 steatohepatitis (NASH)/17 fatty liver (NAFL)] and 33 controls without liver disease. We compared BMD z-scores by multivariable regression, adjusting for known BMD determinants and potential mediators (inflammatory and insulin resistance measures). RESULTS: Unadjusted mean BMD z-scores in NAFLD were similar to controls, but significantly lower in NASH vs. NAFL at all sites. After covariate adjustment, mean forearm BMD z-score was higher in NAFL (ß 0.60 ± SE 0.30, p < 0.05) and lower in NASH (ß - 0.49 ± SE 0.26, p = 0.06) vs. controls (p = 0.002 for group), with similar trends at whole body and total hip; hs-CRP negatively associated with whole body and forearm BMD z-scores (p < 0.05), while visceral fat area negatively associated with femoral neck (p < 0.05). Only three children had clinically low whole body BMD z-scores (< - 2), one per group (control, NAFL and NASH). CONCLUSIONS: NASH, but not NAFL, may be associated with increased risk of reduced BMD in children. Systemic inflammation, independent of body composition and load bearing, may mediate reduction in BMD in NASH.