Differences of 25-hydroxyvitamin D3 concentrations in children and adults with neurofibromatosis type 1

OBJECTIVES: Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disorder, frequently associated with reduced bone mineral density. Serum 25-hydroxyvitamin D3 concentrations in NF1 adults are lower than in healthy controls in autumn respectively winter and are inversely correlated with the number of dermal neurofibromas. We investigated 25-hydroxyvitamin D3 levels in children and adults with neurofibromatosis type 1 in winter and summer and compared them to healthy controls to get more pathogenic insights in vitamin D3 metabolism in NF1 patients.

DESIGN AND METHODS: NF1 patients were clinically examined and serum 25-hydroxyvitamin D3 concentrations were measured in 58 NF1 adults and 46 children in winter as well as in summer and compared to sex-, age- and month-matched controls.

RESULTS: 52 adults suffered from 10 to 5000 dermal neurofibromas, whereas none of the children presented neurofibromas. 25-Hydroxyvitamin D3 increased from winter to summer (mean: 21.0 to 46.5nmol/l) in NF1 adults. This increase was even larger (p=0.0001) than in healthy controls (mean: 50.5 to 60.5nmol/l). However, there were no differences of 25-hydroxyvitamin D3 concentrations in NF1 children and healthy controls both in winter and in summer.

CONCLUSIONS: Only adults with NF1 showed lower 25-hydroxyvitamin D3 levels in winter and summer, which are unlikely due to impaired UV-dependent dermal synthesis, but rather might be caused by an accelerated catabolism.