Reduced bone mineral content and density in neurofibromatosis type 1 and its association with nutrient intake.

Abstract

BACKGROUND Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disease characterized by multisystem involvement including low bone mineral density (BMD). OBJECTIVE To assess the bone phenotype of individuals with NF1 and verify its association with nutrient intake. METHODS Twenty-six adults with NF1 underwent bone phenotype assessments using dual-energy X-ray absorptiometry (DXA) and food intake evaluations. They were compared to 26 unaffected matched control patients. Weight, height, and waist circumference (WC) were measured. DXA provided total body, spine, and hip BMDs and bone mineral content (BMC) for all patients. Food intake was evaluated for energy, macro- and micro-nutrients. RESULTS Height (1.68 ± 0.1; 1.61 ± 0.1 cm; P = 0.003) and BMC (2.3 ± 0.4; 2.0 ± 0.5 kg; P = 0.046) were lower in the NF1 group. Individuals with NF1 also presented lower total body and spine BMDs (g/cm2) (1.1 ± 0.1, 1.0 ± 0.1, P = 0.036; 1.0 ± 0.1, 0.9 ± 0.1; P = 0.015, respectively). The frequency of total body bone mass below the expected level for patients' ages was higher in the NF1 group (7.7%; 34.6%, P = 0.016). There were no differences in energy consumption. No correlations between BMC and BMD with nutrient intake were observed in the NF1 group. CONCLUSIONS The NF1 group presented lower BMCs and BMDs. Although a lower consumption of calcium, iron, and vitamin A, and a higher intake of sodium and omega-6 were observed, there was no relationship between bone phenotype and nutrient intake.