title: High bone mineral apparent density in children with X-linked hypophosphatemia.
abstract: Bone mineral apparent density (BMAD) in children with X-linked hypophosphatemia (XLH) was evaluated, as they are unlikely to have extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients. Children with XLH also had significantly higher BMAD of the spine compared to femoral neck.
  
  
  BACKGROUND
  BMAD obtained by dual-energy X-ray absorptiometry scans in children with XLH was evaluated, as they are unlikely to have the extra-skeletal ossifications contributing to the elevated bone mineral density of the spine in adult patients.
  
  
  METHODS
  A total of 15 children with biochemically and genetically verified XLH were recruited. Anthropometric measurements were performed, and to correct for the short stature (small bones), the BMAD of the spine and the femoral neck was evaluated.
  
  
  RESULTS
  Z-scores of BMAD of the spine (mean (95 % CI); 2.0 (1.3-2.7); p < 0.001) were significantly elevated compared to reference children. Z-scores of the femoral neck (1.0 (-0.0 to 2.1); p = 0.059) tended to be elevated. Spine Z-scores were significantly higher than the Z-scores of the femoral neck, (paired t test, p = 0.02). BMAD of the spine was evaluated according to the Molgaard's approach; XLH children had normal bone size of the spine for age due to a normal sitting height Z-score of -0.4 (-1.0 to 0.1); p = 0.1. Z-scores of bone mineral content (BMC) of the spine for bone area were elevated (1.4 (0.8-2.1); p < 0.001). No reference data were available to allow evaluation of the BMAD of the femoral neck by the Molgaard's approach.
  
  
  CONCLUSIONS
  Children with XLH have an increased BMAD and a high BMC for bone area at the lumbar spine, and this was due to causes other than extra-skeletal ossifications and corrected for bone size. The BMAD of the spine was significantly higher compared to the femoral neck.
authors: Institute of Clinical Research, University of Southern Denmark, Winsløwparken 19.3, 5000, Odense C, Denmark. sbeck-nielsen@health.sdu.dk
authors: S S
authors: SS
authors: Beck-Nielsen
authors: K
authors: K
authors: Brixen
authors: J
authors: J
authors: Gram
authors: C
authors: C
authors: Mølgaard
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000293:Adolescent; D000886:Anthropometry / Q000379:methods; D001827:Body Height / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D002648:Child; D053098:Familial Hypophosphatemic Rickets / Q000503:physiopathology*; D005260:Female; D005272:Femur Neck / Q000503:physiopathology; D006801:Humans; D008159:Lumbar Vertebrae / Q000503:physiopathology; D008297:Male; D012016:Reference Values
references: Metab Bone Dis Relat Res. 1981;3(3):159-64
references: 6290833
references: Bone Miner. 1992 Apr;17(1):75-85
references: 1581707
references: Medicine (Baltimore). 1989 Nov;68(6):336-52
references: 2811660
references: Hum Mol Genet. 1997 Feb;6(2):165-71
references: 9063736
references: Am J Physiol Endocrinol Metab. 2011 Mar;300(3):E508-17
references: 21139072
references: J Pediatr. 1995 Sep;127(3):395-402
references: 7658269
references: J Clin Endocrinol Metab. 2010 Mar;95(3):1265-73
references: 20103654
references: Calcif Tissue Int. 1996 Nov;59(5):344-51
references: 8849400
references: Bone Miner. 1991 Feb;12(2):91-100
references: 2015415
references: Clin Nucl Med. 1993 Jul;18(7):564-6
references: 8344024
references: Skeletal Radiol. 2000 Feb;29(2):90-3
references: 10741497
references: Radiology. 1989 May;171(2):403-14
references: 2539609
references: J Clin Invest. 1981 Mar;67(3):911-4
references: 6259210
references: Anat Rec A Discov Mol Cell Evol Biol. 2003 Dec;275(2):1081-101
references: 14613308
references: Acta Paediatr Scand. 1984 Mar;73(2):181-4
references: 6331056
references: N Engl J Med. 1980 Oct 30;303(18):1023-31
references: 6252463
references: J Bone Miner Res. 1992 Feb;7(2):137-45
references: 1570758
references: J Bone Miner Res. 2001 Apr;16(4):597-604
references: 11315987
references: J Clin Endocrinol Metab. 1992 Sep;75(3):879-85
references: 1517380
references: Ugeskr Laeger. 1995 Dec 4;157(49):6876-81
references: 7491733
references: Endocr Dev. 2003;6:69-79
references: 12964426
references: J Bone Miner Metab. 2012 Jan;30(1):1-9
references: 22167381
references: Clin Nephrol. 1996 Jan;45(1):33-41
references: 8616955
references: Eur J Endocrinol. 2009 Mar;160(3):491-7
references: 19095780
references: Calcif Tissue Int. 1989 Feb;44(2):86-92
references: 2492895
references: Arch Dis Child. 1997 Jan;76(1):9-15
references: 9059153
references: J Musculoskelet Neuronal Interact. 2006 Apr-Jun;6(2):142-6
references: 16849823
references: Metab Bone Dis Relat Res. 1981;3(1):31-8
references: 6267414
references: J Hum Genet. 2012 Jul;57(7):453-8
references: 22695891
references: Arch Dis Child. 2007 Jan;92(1):53-9
references: 16943261
references: Am J Med. 1991 Jan;90(1):63-9
references: 1986592
references: J Clin Endocrinol Metab. 1998 May;83(5):1414-9
references: 9589631
references: Pediatr Radiol. 2007 Jan;37(1):21-31
references: 16715219
references: Pediatr Res. 2003 Jul;54(1):125-36
references: 12700367
references: Pediatr Nephrol. 1997 Oct;11(5):573-7
references: 9323282
references: Ugeskr Laeger. 1982 Jun 14;144(24):1760-5
references: 7135585
references: Calcif Tissue Int. 2010 Aug;87(2):108-19
references: 20524110
references: J Clin Endocrinol Metab. 1991 Dec;73(6):1332-9
references: 1955516
references: J Pediatr. 2001 Feb;138(2):236-43
references: 11174622
references: Metabolism. 1976 Jan;25(1):33-40
references: 173975
references: Pediatr Nephrol. 2010 Jan;25(1):37-47
references: 19603190
references: Pediatr Nephrol. 2011 Feb;26(2):223-31
references: 21120538
references: J Bone Miner Res. 2011 Jul;26(7):1381-8
references: 21538511
references: N Engl J Med. 1969 Sep 4;281(10):512-6
references: 5800510