Clinical Study Oral Postdialysis Cholecalciferol Supplementation in Patients on Maintenance Hemodialysis: A Dose-Response Approach Eric Descombes, 1 Benoit Fellay, 2 Ould Maouloud Hemett, 1 Jean-Luc Magnin, 2 and Gilbert Fellay 1 1 Service of Nephrology, HFR Hˆ opital Cantonal, 1708 Fribourg, Switzerland 2 Central Laboratory, HFR Hˆ opital Cantonal, 1708 Fribourg, Switzerland Correspondence should be addressed to Eric Descombes; descombese@h-fr.ch Received 2 September 2013; Accepted 2 November 2013; Published 21 January 2014 Academic Editor: Vladim´ ır Tesaˇ r Copyright © 2014 Eric Descombes et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Te aim of the present study was to evaluate the dose of postdialysis cholecalciferol needed to maintain the 25-hydroxyvitamin D [25(OH)D] levels in the optimal range of 75–150nmol/L. Twenty-six patients who had low baseline 25(OH)D levels (mean 27.5 ± 14.9 nmol/L) were studied. Te 25(OH)D levels were measured every 2 months for one year. During the frst two months, all the patients received 2000 IU of cholecalciferol afer each hemodialysis (=6000 IU/wk). Tereafer, the dose was individualized and adapted every 2 months by administering 1 to 6 cholecalciferol tablets (2000 IU each) per week (total weekly dose = 2000– 12000IU/wk). During cholecalciferol supplementation, the 25(OH)D concentrations rapidly increased from baseline to 140.1 ± 28.3 nmol/L at month 6 and 95.6 ± 20.9 nmol/L at month 12. At month twelve, 86% of the patients had 25(OH)D levels within the target range with a mean dose of 5917 ± 4106 IU/wk of cholecalciferol; however, the amount needed to maintain these levels varied widely from 0 (=2) to 12000 IU/wk (=5). In conclusion, postdialysis cholecalciferol prescription is quite efective in correcting vitamin D defciency/insufciency, but the amount of cholecalciferol needed to maintain the 25(OH)D levels within the optimal range over the long-term varies widely among patients and must be individualized. 1. Introduction Recent important advances have been made in understanding vitamin D physiology, beyond its classic role in mineral and bone metabolism [1–11]. Indeed, recent studies have shown that several tissues, in addition to the kidneys, express the enzyme CYP27B1, which catalyzes the 1-hydroxylation of 25(OH)D, and that the vitamin D receptor (VDR) is expressed ubiquitously [1–11]. It is now known that a con- version of 25(OH)D to 1,25-dihydroxyvitamin D (calcitriol, the active form of vitamin D) occurs in several extrarenal cells and may be associated with signifcant biological roles beyond those traditionally attributed to vitamin D [1–11]. As a consequence, there has been a great deal of interest in the study of these nonclassical autocrine/intracrine efects of vitamin D during the past few years and a signifcant body of information in the medical literature has shown that vitamin D defciency/insufciency is associated with several abnormalities such as an increased risk of cardiovascular, musculoskeletal and autoimmune diseases, cancer, infec- tions, diabetes, and mortality [1–6, 12–27]. As a result, the possible benefts of vitamin D supplementation in patients with low levels became the focus of interest of the scientifc community and studies have even reported an improved survival in patients receiving cholecalciferol supplements [28, 29]. Accordingly, recent recommendations support the supplementation of vitamin D—with a dose equivalent to at least 800 IU per day—in a variety of clinical conditions, including chronic kidney disease (CKD) and, according to a majority of experts, the objective should be to achieve 25(OH)D concentrations of at least 75 nmol/L for an optimal health beneft [1, 6, 8, 30–39]. In patients who have CKD or who are on maintenance hemodialysis (HD) vitamin D defciency/insufciency is very widespread [9–11, 39–56]. Recent guidelines also recom- mend giving oral vitamin D supplementation to patients on Hindawi Publishing Corporation International Journal of Nephrology Volume 2014, Article ID 597429, 10 pages http://dx.doi.org/10.1155/2014/597429