title: Alterations in proximal femur geometry in children treated with glucocorticoids for Crohn disease or nephrotic syndrome: impact of the underlying disease.
abstract: Proximal femur geometry was assessed in children and young adults treated with chronic GCs for CD or SSNS. Subperiosteal width and section modulus were significantly lower in CD and greater in SSNS compared with controls, highlighting the importance of the underlying disease, persistent inflammation, and alterations in lean mass.
  
  
  BACKGROUND
  The impact of glucocorticoid (GC) therapy on bone structure during growth is unknown. Our objective was to characterize proximal femur geometry in children and young adults with Crohn disease (CD) or steroid-sensitive nephrotic syndrome (SSNS) compared with controls and to evaluate the influence of lean mass and GC therapy on bone parameters.
  
  
  METHODS
  DXA scans of the hip and whole body were obtained in 88 subjects with CD, 65 subjects with SSNS, and 128 controls (4-26 years of age). Hip structural analysis parameters (subperiosteal width, cross-sectional area [CSA], and section modulus in the narrow neck [NN], intertrochanteric region [IT], and femoral shaft [FS]), areal BMD, and whole body lean mass were expressed as Z scores compared with controls. Multivariable linear regression was used to adjust outcomes for group differences in age, sex, race, and height.
  
  
  RESULTS
  Mean lean mass Z scores were lower in CD (-0.63, p < 0.001) and greater in SSNS (0.36, p = 0.03) compared with controls. Hip areal BMD Z scores were lower in CD (-0.73, p < 0.001) but not SSNS (-0.02, p > 0.2) compared with controls. In CD, Z scores for subperiosteal width (NN: -1.66, p < 0.001; FS: -0.86, p < 0.001) and section modulus (NN: -0.60, p = 0.003; FS: -0.36, p = 0.03) were significantly lower than controls. In contrast, in SSNS, Z scores were greater for IT subperiosteal width (0.39, p = 0.02), FS CSA (0.47, p = 0.005), and FS section modulus (0.49, p = 0.004). Alterations in section modulus in CD and SSNS were eliminated after adjustment for lean mass. Cumulative GC dose was inversely associated with FS subperiosteal width and section modulus only in CD.
  
  
  CONCLUSIONS
  These data show that the effects of GC on proximal femur geometry during growth are influenced by the underlying disease, persistent inflammation, and alterations in lean mass. These data also provide insight into the structural basis of hip fragility in CD.
authors.affiliation: The Children's Hospital of Philadelphia, Philadelphia PA 19104, USA. burnhams@email.chop.edu
authors.forename: Jon M
authors.initials: JM
authors.lastname: Burnham
authors.forename: Justine
authors.initials: J
authors.lastname: Shults
authors.forename: Moira A
authors.initials: MA
authors.lastname: Petit
authors.forename: Edisio
authors.initials: E
authors.lastname: Semeao
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Beck
authors.forename: Babette S
authors.initials: BS
authors.lastname: Zemel
authors.forename: Mary B
authors.initials: MB
authors.lastname: Leonard
mesh_terms: D000293:Adolescent; D000328:Adult; D015519:Bone Density / Q000187:drug effects*; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D003424:Crohn Disease / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D004351:Drug Resistance; D005260:Female; D005269:Femur / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D005938:Glucocorticoids / Q000009:adverse effects*; D006801:Humans; D008297:Male; D009404:Nephrotic Syndrome / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology*; D010024:Osteoporosis / Q000139:chemically induced
chemical_list: D005938:Glucocorticoids