title: Diagnosis of low bone mass in CKD-5D patients.
abstract: OBJECTIVE
  Currently, there is no consensus whether dual-energy X-ray absorptiometry (DXA) or quantitative computed tomography (QCT) can be used to screen for osteoporosis or osteopenia in CKD-5D patients. This study uses iliac bone histology, the "gold standard" for bone volume evaluation, to determine the utility of DXA and QCT for low bone mass screening in CKD-5D patients.
  
  
  METHODS
  A cross-sectional study of patients with CKD-5D employing iliac crest bone biopsies to assess bone volume by histology and comparing results to bone mineral density (BMD) measurements of the hip and spine by DXA and QCT. Pearson's correlation, linear regression, and receiver operating characteristics curve analyses were performed.
  
  
  RESULTS
  46 patients (mean age 51 years, 52% women, median dialysis vintage 46 months) had bone biopsies, DXA, and QCT scans. 37 patients (80%) had low bone volume by histology. DXA and QCT BMD values (g/cm2) were very highly correlated at the femoral neck (ρ = 0.97) and total hip (ρ = 0.97), and to a lesser degree at the spine (ρ = 0.65). DXA and QCT t-scores were also highly correlated, but QCT t-scores were systematically greater than DXA t-scores (1.1 S.D. on average at the femoral neck) leading to less recognition of osteopenia and osteoporosis by QCT. A t-score below -1 by DXA at the femoral neck (i.e., osteopenic or osteoporotic) showed 83% sensitivity and 78% specificity relative to low bone volume by histology. A QCT t-score below -1 did not reach acceptable diagnostic levels of sensitivity and specificity.
  
  
  CONCLUSIONS
  DXA and QCT provide nearly identical areal BMD measures at the hip. However, QCT t-scores are consistently higher than DXA t-scores resulting in less diagnosis of osteoporosis or osteopenia. DXA results showed acceptable diagnostic sensitivity and specificity for low bone volume by histology and can be used for diagnosis of osteopenia and osteoporosis in patients with CKD-5D.
authors.forename: Gustav A
authors.initials: GA
authors.lastname: Blomquist
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Davenport
authors.forename: Hanna W
authors.initials: HW
authors.lastname: Mawad
authors.forename: Marie-Claude
authors.initials: MC
authors.lastname: Monier-Faugere
authors.forename: Hartmut H
authors.initials: HH
authors.lastname: Malluche
mesh_terms: D015502:Absorptiometry, Photon / Q000706:statistics & numerical data*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy / Q000379:methods; D015519:Bone Density / Q000502:physiology*; D001851:Bone Diseases, Metabolic / Q000000981:diagnostic imaging*; D003430:Cross-Sectional Studies; D005260:Female; D005272:Femur Neck / Q000000981:diagnostic imaging; D006801:Humans; D007085:Ilium / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D011446:Prospective Studies; D012372:ROC Curve; D051436:Renal Insufficiency, Chronic / Q000150:complications*; D012680:Sensitivity and Specificity; D013131:Spine / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed / Q000706:statistics & numerical data*; D055815:Young Adult