title: Evaluation of bone mineral density and microarchitectural parameters by DXA and HR-pQCT in 37 children and adults with X-linked hypophosphatemic rickets.
abstract: In X-linked hypophosphatemic (XLH) rickets, dual-energy X-ray absorptiometry (DXA) measurements must be analyzed with caution. High-resolution peripheral quantitative computed tomography (HR-pQCT) analysis suggested that XLH primarily affects the cancellous compartment, with the tibia more affected than the radius. Effective treatment of XLH appears to positively affect bone mineralization, mainly in the bone cortex.
  
  
  
  The purpose of this study is to evaluate bone mineral density (BMD) and microarchitecture in 37 patients (13 children and 24 adults) with XLH confirmed by PHEX mutations from a tertiary center compared to healthy controls.
  
  
  
  Areal BMD (aBMD) was evaluated by DXA, whereas volumetric BMD (vBMD) and microarchitectural parameters were analyzed by HR-pQCT.
  
  
  
  Adult XLH patients had higher lumbar aBMD (p < 0.01) than the controls. At the radius, the vBMD was similar between XLH patients and controls. At the tibia, XLH patients had lower total vBMD (p = 0.04), likely resulting from decreased trabecular vBMD (p < 0.01), and this difference was observed in the children and adult groups. Analysis based on metabolic status showed that the adult XLH patients with non-compensated disease had lower cortical vBMD at the tibia than the compensated XLH patients (p = 0.03). The microarchitectural differences at the radius and tibia included lower trabecular number (p < 0.01), greater trabecular separation (p < 0.01), and higher trabecular network inhomogeneity (p < 0.01) in XLH patients compared to their controls. At the radius, adults exhibited greater trabecular deficits than were seen in children.
  
  
  
  In XLH patients, DXA measurements must be analyzed with caution due to the interference of anatomic and anthropometric factors. HR-pQCT analysis suggested that XLH primarily affects the cancellous compartment, with the tibia more affected than the radius. Effective treatment of XLH appears to positively affect bone mineralization, mainly in the bone cortex.
authors.affiliation: Osteometabolic Disorders Unit, Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 8° andar, Bloco 3, São Paulo, SP, 05403-900, Brazil.|Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 2° andar, Bloco 6, São Paulo, SP, 05403-900, Brazil.
authors.forename: G P
authors.initials: GP
authors.lastname: Colares Neto
authors.affiliation: Bone Metabolism Laboratory (LIM/17), Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 455, 3° andar, Sala 3193, São Paulo, SP, 01246-903, Brazil.
authors.forename: R M R
authors.initials: RM
authors.lastname: Pereira
authors.affiliation: Bone Metabolism Laboratory (LIM/17), Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 455, 3° andar, Sala 3193, São Paulo, SP, 01246-903, Brazil.
authors.forename: J C
authors.initials: JC
authors.lastname: Alvarenga
authors.affiliation: Bone Metabolism Laboratory (LIM/17), Rheumatology Division, Faculdade de Medicina da Universidade de São Paulo, Av. Dr. Arnaldo, 455, 3° andar, Sala 3193, São Paulo, SP, 01246-903, Brazil.
authors.forename: L
authors.initials: L
authors.lastname: Takayama
authors.affiliation: Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 2° andar, Bloco 6, São Paulo, SP, 05403-900, Brazil.
authors.forename: M F A
authors.initials: MF
authors.lastname: Funari
authors.affiliation: Osteometabolic Disorders Unit, Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 8° andar, Bloco 3, São Paulo, SP, 05403-900, Brazil. reginamm@usp.br.|Hormone and Molecular Genetics Laboratory (LIM/42), Endocrinology Division, Hospital das Clínicas da Universidade de São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 155 - PAMB, 2° andar, Bloco 6, São Paulo, SP, 05403-900, Brazil. reginamm@usp.br.
authors.forename: R M
authors.initials: RM
authors.lastname: Martin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D015519:Bone Density / Q000502:physiology*; D002648:Child; D053098:Familial Hypophosphatemic Rickets / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011884:Radius / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D013977:Tibia / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D014057:Tomography, X-Ray Computed / Q000379:methods; D055815:Young Adult
keywords: Bone microarchitecture; Bone mineral density; DXA; HR-pQCT; X-linked hypophosphatemic rickets