Pediatric 25-hydroxyvitamin D concentrations in neurofibromatosis type 1

Objective: Low 25-hydroxyvitamin D (25OHD) concentrations have been associated with tumors and osteopenia or fractures in adults with neurofibromatosis type 1 (NF1). We report 25OHD concentrations in 109 children with NF1 and 218 controls matched for age, sex, geographic location, and time of year. Methods: Children with NF1 were recruited (n=109; 2-17 years), and clinical data and dual-energy X-ray absorptiometry measurements were obtained. 25OHD concentrations were measured in subjects and controls. Results: More NF1 individuals (50%) were in the 25OHD insufficient or deficient range (<30 ng/mL) (1 ng/mL=2.496 nmol/L) compared to controls (36%) (p=0.0129). 25OHD concentrations were higher in individuals with neurofibromas after controlling for age (p=0.0393), and were negatively associated with whole-body subtotal bone mineral density (BMD) z-scores (p=0.0385). Conclusions: More children with NF1 had 25OHD concentrations <30 ng/mL, potentially because of increased pigmentation and/or decreased sunlight exposure. In contrast to adults, decreased 25OHD concentrations were not associated with neurofibromas, and there was no positive association between 25OHD and BMD.