The
neurofibromatosis type 1 (NF1) is characterized by specific cutaneous features (
neurofibromas, "café-au-lait" spots of the skin) and alterations of several tissue (nervous, vascular) and bone
deformities, such as
scoliosis,
congenital pseudoarthrosis and
bone dysplasia of tibia. Moreover, several studies have shown systemic involvement of bone tissue in NF1 patients, leading to reduced bone mass. The aim of our study was to evaluate some bone
mineral metabolism parameters before and after
calcium and
vitamin D supplementation in NF1 patients. We evaluated in 70 NF1 consecutive patients the
mineral metabolism and bone mineral density compared with 40 normal subjects. We showed bone alterations in 35% of patients and the increase of bone formation markers, such as bone
isoenzyme of
alkaline phosphatase (41.2 ± 15.5 vs. 25.6 ± 8.7 UI; P < 0.05, respectively) and
osteocalcin (18.1 ± 5.6 vs. 7.6 ± 1.9 ng/ml; P < 0.05) and reduction of circulating levels of (25OH)-vitamin D (21.8 ± 12.3 ng/ml) with an high percentage of hypovitaminosys D (>60%). Moreover, we revealed a significant reduction of bone mass density at spine (L1-L4) (0.935 ± 0.13 vs. 1.110 ± 0.17 g/cm(2); P < 0.001) and femoral neck side (0.765 ± 0.09 vs. 0.839 ± 0.12 g/cm(2); P < 0.02), with high prevalence of
osteopenia (44%) and
osteoporosis (18%). After 12 months of
calcium (1,200 mg/die) and
cholecalciferol (800 UI/die) supplementation, we found a significant increase of (25)
OH-
vitamin D level (21.8 ± 12.3 vs. 35 ± 13 ng/ml; P < 0.01), without changes in bone mass density. In conclusion, NF1 patients may present a
mineral bone involvement, with
vitamin D deficiency;
calcium and
vitamin D supplementation is necessary to restore these bone
mineral metabolic alterations.