title: The association between body composition, 25(OH)D, and PTH and bone mineral density in black African and Asian Indian population groups.
abstract: OBJECTIVE
  There are few data on the contribution of body composition to bone mineral density (BMD) in non-Caucasian populations. We therefore studied the contribution of body composition, and possible confounding of 25-hydroxyvitamin D and PTH, to BMD at various skeletal sites in black African (BA) and Asian Indian (AI) subjects.
  
  
  METHODS
  This was a cross-sectional study in Johannesburg, South Africa.
  
  
  METHODS
  BMD, body fat, and lean mass were measured using dual x-ray absorptiometry and abdominal fat distribution by ultrasound in 714 healthy subjects, aged 18-65 years.
  
  
  RESULTS
  Whole-body (subtotal), hip, femoral neck, and lumbar spine (lumbar) BMD were significantly higher in BA than AI subjects (P < .001 for all). Whole-body lean mass positively associated with BMD at all sites in both ethnic groups (P < .001 for all) and partially explained the higher BMD in BA females compared with AI females. Whole-body fat mass correlated positively with lumbar BMD in BA (P = .001) and inversely with subtotal BMD in AI subjects (P < .0001). Visceral adiposity correlated inversely with subtotal BMD in the BA (P = .037) and with lumbar BMD in the AI group (P = .005). No association was found between serum 25-hydroxyvitamin D and BMD. PTH was inversely associated with hip BMD in the BA group (P = .01) and with subtotal (P = .002), hip (P = .001), and femoral BMD (P < .0001) in the AI group.
  
  
  CONCLUSIONS
  Significant differences in whole-body and site-specific BMD between the BA and AI groups were observed, with lean mass the major contributor to BMD at all sites in both groups. The contribution of other components of body composition differed by site and ethnic group.
authors.affiliation: Department of Chemical Pathology (J.G., N.J.C.), National Health Laboratory Service and University of the Witwatersrand, and Medical Research Council/Wits Developmental Pathways for Health Research Unit (L.K.M., S.A.N.), Department of Paediatrics, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa.
authors.forename: Jaya A
authors.initials: JA
authors.lastname: George
authors.forename: L K
authors.initials: LK
authors.lastname: Micklesfield
authors.forename: S A
authors.initials: SA
authors.lastname: Norris
authors.forename: N J
authors.initials: NJ
authors.lastname: Crowther
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People / Q000706:statistics & numerical data*; D044383:Black People / Q000706:statistics & numerical data*; D001823:Body Composition; D015519:Bone Density; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D013019:South Africa / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D055815:Young Adult
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D