Vitamin D deficiency and associated factors in hemodialysis patients

Background: Vitamin D deficiency is prevalent in the general elderly population, and is related to an increased risk of osteoporosis, fractures, and cardiovascular calcification. Only limited data and no guidelines are available on vitamin D deficiency in hemodialysis patients. Objective: We aimed to assess the frequency of, and factors associated with, 25(OH) vitamin D deficiency in hemodialysis patients in a French dialysis center. Design: In March 2006, we studied all prevalent hemodialysis patients who had not received native vitamin D supplements in the recent past. According to the Kidney Disease Outcomes and Quality Initiative guidelines, patients were assigned to the following 3 groups: group 1, with a sufficient vitamin D serum level (>75 nmol/L); group 2, with an insufficient level (25 to 75 nmol/L); and group 3, with severe deficiency (<25 nmol/L). Patients' characteristics and biochemical findings were compared between patients of groups 1 and 3. Results: Of 253 patients, 11 % patients were in group 1; 47% were in group 2; and 42% were in group 3. The proportions of female and diabetes patients were 42% and 34%, respectively. The mean ( +/- SD) age of all patients was 66.7 +/- 14 years, and the mean duration of dialysis was 62 +/- 74 months, with a mean schedule of 3 x 6.5 hours and administration of a 1.5 mmol/L calcium dialysate. Concomitant treatment included alfacalcidol (66% of patients) and sevelamer (34% of patients) as a standard phosphate binder. Group 3 patients had a lower dialysis vintage (53 66 vs. 73 +/- 85 months, P <.05), a higher number of diabetes patients (45% vs. 21 %, P <.05), a higher number of female patients (53% vs. 28%, P <.05), and a higher level of intact parathyroid hormone (260 +/- 227 vs. 213 +/- 153 pg/mL, P <.05) than group 1 patients. No relationship was found between vitamin D storage levels and bone markers, serum calcium, phosphorus, albumin, body mass index, normalized protein catabolic rate, radiologic vascular calcification score, and hip bone mineral density. In multivariate logistic regression analyses, no factors were significantly associated with vitamin D deficiency. Conclusions: Calcidiol deficiency was highly prevalent in a French dialysis population. The associated factors mainly included female sex, diabetes, shorter dialysis duration, and higher intact parathyroid hormone level. Although there are no guidelines for the therapy of patients with chronic kidney disease at stage 5, the usefulness of vitamin D supplementation may be assessed by considering its potential direct action, the need for providing fuel for renal and extrarenal calcitriol production in particular, and the numerous potential favorable effects on health. (C) 2008 by the National Kidney Foundation, Ins. All rights reserved.