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Keywords:

  • 25-hydroxyvitamin D;
  • chronic kidney disease;
  • diabetes;
  • BMD;
  • fracture

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.

Introduction: 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 m2 or on dialysis), but it is unclear if this deficiency is associated with bone disease and if supplementation is warranted.

Materials and 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.