title: 25-Hydroxyvitamin D deficiency and diabetes predict reduced BMD in patients with chronic kidney disease.
abstract: In this study of 242 patients with renal failure, women, patients with diabetes, and patients on peritoneal dialysis had the highest risk of 25-hydroxyvitamin D deficiency. Levels correlated positively to BMD Z scores, and hip BMD was inversely related to prevalent fracture. Increasing 25-hydroxyvitamin D levels may benefit these patients.
  
  
  BACKGROUND
  25-Hydroxyvitamin D deficiency (<37 nM) is common in patients with chronic kidney disease (CKD) stage 5 (glomerular filtration rate < 15 ml/min/1.73 m(2) or on dialysis), but it is unclear if this deficiency is associated with bone disease and if supplementation is warranted.
  
  
  METHODS
  Blood samples were collected on 242 patients with CKD stage 5 caused by type 1 diabetes (33%), type 2 diabetes (2%), and other causes (65%), who were about to undergo kidney or kidney pancreas transplantation. Prevalent spinal fracture was assessed by X-ray and BMD by DXA.
  
  
  RESULTS
  25-Hydroxyvitamin D deficiency was present in 28% of patients with diabetes versus 12% without (p < 0.0001). Patients on peritoneal dialysis (PD) had lower levels of 25-hydroxyvitamin D than patients on hemodialysis (HD; 49 +/- 26 versus 77 +/- 34 nM; p < 0.0001), and women had lower levels than men (51 +/- 25 versus 77 +/- 35 pM; p < 0.0001). BMD Z scores were within 1 SD of the mean at all sites, except in patients with diabetes (femoral neck Z score, -1.07 +/- 1.2; p < 0.0001) and patients who had undergone parathyroidectomy (lumbar spine Z score, 1.03 +/- 1.34, femoral neck Z score, 1.24 +/- 1.35; p < 0.001 and p < 0.0001, respectively). In multiple stepwise linear regression analysis, levels of 25-hydroxyvitamin D correlated positively and intact PTH (iPTH) correlated negatively to Z scores at the lumbar spine and wrist. Time on dialysis correlated positively to Z scores at the femoral neck and lumbar spine. Diabetes and serum alkaline phosphatase levels correlated negatively with Z scores at the femoral neck. Lower femoral neck BMD was associated with an increased prevalence of vertebral fracture and fragility fracture at any site (p = 0.03 and p < 0.03, respectively).
  
  
  CONCLUSIONS
  This study of patients with CKD stage 5 identifies women, patients with diabetes, and patients on PD as being at particular risk of 25-hydroxyvitamin D deficiency. We describe positive associations of 25-hydroxyvitamin D levels and BMD Z scores and an association between femoral neck BMD and fragility fracture at any site. Treatment to improve 25-hydroxyvitamin D levels may benefit these patients.
authors.affiliation: Centre for Transplant and Renal Research, Westmead Millennium Institute, Sydney, New South Wales, Australia. g.elder@garvan.unsw.edu.au
authors.forename: Grahame J
authors.initials: GJ
authors.lastname: Elder
authors.forename: Kenneth
authors.initials: K
authors.lastname: Mackun
mesh_terms: D000328:Adult; D015519:Bone Density; D048909:Diabetes Complications / Q000473:pathology*; D003920:Diabetes Mellitus / Q000473:pathology*; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000150:complications* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000150:complications*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D