There is an increased risk of osteoporosis and an abnormal bone turn over in neurofibromatosis 1 (NF1). Our objective is to evaluate bone status in NF1 and to look for associations with cutaneous phenotype. We conducted a descriptive, monocentric study. We included 60 NF1 women, 18–51 years old, non-menopausal, divided in 2 groups: «at risk phenotype» (ARP) composed by 30 patients with at least 2 subcutaneous neurofibromas (SC-NF) and «classical phenotype» (CP) composed by 30 patients with none or 1 SC-NF. We evaluated low bone mineral density (BMD) risk factors and measured BMD, calcium and phosphorus homeostasis and bone turnover markers. Before 50 years old, Z-score has to be used to assess BMD. Z-score < − 2 is below expected range and represents 2.5% of the population. There was no difference between the two groups. Overall, Z-scores were low and 5 patients had a Z-score < − 2 (8.3%), which is 3 times general population low BMD frequency. 10 fragility fractures occurred in 8 patients, among which 2 were vertebral fractures. 85% had low calcium intake. 12 patients had hypophosphoremia, 25 elevated PTH. Vitamin D levels were low for 86.4%. 41 patients (69.5%) had at least one abnormal bone turnover markers. Low BMD is 3.3 times more frequent in NF1 than in general population, with high fracture risk, regardless of the skin phenotype, classical or at risk, because of high bone turn over and secondary hyperparathyroidism due to vitamin D deficiency and poor calcium intake.

在神经纤维瘤病 1 (NF1) 中，骨质疏松症和异常骨翻转的风险增加。我们的目标是评估 NF1 的骨骼状态并寻找与皮肤表型的关联。我们进行了描述性的单中心研究。我们纳入了 60 名 NF1 女性，年龄在 18-51 岁，未绝经，分为 2 组：由 30 名至少有 2 个皮下神经纤维瘤 (SC-NF) 和“经典表型”的患者组成的“高危表型”(ARP)（ CP）由 30 名无 SC-NF 或 1 个 SC-NF 的患者组成。我们评估了低骨矿物质密度 (BMD) 风险因素并测量了 BMD、钙磷稳态和骨转换标志物。50岁之前，必须使用Z- score来评估BMD。Z-score < − 2 低于预期范围，代表 2.5% 的人口。两组之间没有差异。总体而言，Z分数较低，5 名患者的Z分数 < - 2 (8.3%)，是一般人群低 BMD 频率的 3 倍。8例患者发生脆性骨折10例，其中椎体骨折2例。85% 的人钙摄入量低。低磷血症12例，PTH升高25例。维生素 D 水平低至 86.4%。41 名患者 (69.5%) 至少有一种异常骨转换标志物。低 BMD 在 NF1 中的发生率是一般人群的 3.3 倍，骨折风险高，无论皮肤表型如何，经典型或有风险，因为高骨转换和继发性甲状旁腺功能亢进由于维生素 D 缺乏和钙摄入不足。