title: Bone mineral density in children and young adults with neurofibromatosis type 1.
abstract: Concern for impaired bone health in children with neurofibromatosis type 1 (NF-1) has led to increased interest in bone densitometry in this population. Our study assessed bone mineral apparent density (BMAD) and whole-body bone mineral content (BMC)/height in pediatric patients with NF-1 with a high plexiform neurofibroma burden. Sixty-nine patients with NF-1 (age range 5.2-24.8; mean 13.7 ± 4.8 years) were studied. Hologic dual-energy X-ray absorptiometry scans (Hologic, Inc., Bedford, MA, USA) were performed on all patients. BMD was normalized to derive a reference volume by correcting for height through the use of the BMAD, as well as the BMC. BMAD of the lumbar spine (LS 2-4), femoral neck (FN), and total body BMC/height were measured and Z-scores were calculated. Impaired bone mineral density was defined as a Z-score ≤-2. Forty-seven percent of patients exhibited impaired bone mineral density at any bone site, with 36% at the LS, 18% at the FN, and 20% total BMC/height. BMAD Z-scores of the LS (-1.60 ± 1.26) were more impaired compared with both the FN (-0.54 ± 1.58; P=0.0003) and the whole-body BMC/height Z-scores (-1.16 ± 0.90; P=0.036). Plexiform neurofibroma burden was negatively correlated with LS BMAD (r(s)=-0.36, P=0.01). In pediatric and young adult patients with NF-1, LS BMAD was more severely affected than the FN BMAD or whole-body BMC/height.
authors.affiliation: Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA. lodishma@mail.nih.gov
authors.forename: Maya B
authors.initials: MB
authors.lastname: Lodish
authors.forename: Urania
authors.initials: U
authors.lastname: Dagalakis
authors.forename: Ninet
authors.initials: N
authors.lastname: Sinaii
authors.forename: Ethan
authors.initials: E
authors.lastname: Bornstein
authors.forename: Aerang
authors.initials: A
authors.lastname: Kim
authors.forename: Kelsey B
authors.initials: KB
authors.lastname: Lokie
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Baldwin
authors.forename: James C
authors.initials: JC
authors.lastname: Reynolds
authors.forename: Eva
authors.initials: E
authors.lastname: Dombi
authors.forename: Constantine A
authors.initials: CA
authors.lastname: Stratakis
authors.forename: Brigitte C
authors.initials: BC
authors.lastname: Widemann
mesh_terms: D000293:Adolescent; D000328:Adult; D015519:Bone Density; D002648:Child; D002675:Child, Preschool; D005260:Female; D005272:Femur Neck / Q000503:physiopathology; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008297:Male; D018318:Neurofibroma, Plexiform / Q000503:physiopathology*; D009456:Neurofibromatosis 1 / Q000503:physiopathology*; D055815:Young Adult