Risk factors for low bone mineral density in children and young adults with Crohn's disease

Objective: Low bone mineral density (BMD) is a recognized complication of Crohn's disease (CD). The aim of this study was to identify the risk factors for low BMD in pediatric patients with CD. Study Design: One hundred nineteen subjects with CD ranging in age from 5 to 25 years were enrolled. BMD of the lumbar spine was measured by dual-energy x-ray absorptiometry. Growth parameters were assessed by examination. Disease-specific variables and use of selected medications were determined by chart review. Results: Powerful risk factors for low BMD z-score included hypoalbuminemia, exposure to nasogastric tube feeds, total parenteral nutrition, 6-mercaptopurine, and corticosteroids. Corticosteroid dosing at a level >7.5 mg/d, 5000 mg lifetime cumulative dose, or >12 months of lifetime exposure were significant risk factors for low BMD z-score. Weaker but significant associations with low BMD z-scores included measures of disease severity such as pediatric Crohn's disease activity index, hospital admissions, and length of hospital stay. Site and duration of disease were not predictive. Conclusions: The presence of several clinically available factors was predictive of poor bone mineral status in this sample of subjects with CD. Hypoalbuminemia, corticosteroid exposure, nasogastric tube feeds, total parenteral nutrition, and 6-mercaptopurine were the most powerful risk factors for low bone mineral status.