title: Inverse association of serum 25-hydroxyvitamin D with markers of inflammation and suppression of osteoclastic activity in hemodialysis patients.
abstract: BACKGROUND
  In hemodialysis patients, 25-hydroxyvitamin D conversion to active 1,25-dihydroxyvitamin D by the kidneys is very limited. The expression of both vitamin D receptor and 1alpha-hydroxylase in cells of the immune system and in both osteoblasts and osteoclasts makes it possible that 25-hydroxyvitamin D could play an important role in both inflammation and bone metabolism acting in a autocrine and/or paracrine way in these patients.
  
  
  METHODS
  Thirty-three hemodialysis patients not under vitamin D receptor agonist treatment were enrolled into the study. Serum levels of 25-hydroxyvitamin D, C-reactive protein (CRP), interleukin-6 (IL-6), receptor activator of nuclear factor-kappaB ligand (RANKL), and osteoprotegerin, as well as intact parathyroid hormone were assessed by immunoassays.
  
  
  RESULTS
  Regarding inflammation, 25-hydroxyvitamin D inversely correlated with both CRP and IL-6. Regarding bone metabolism, 25-hydroxyvitamin D was positively related to osteoprotegerin, but negatively to the RANKL. The latter could be the result of parathyroid hormone suppression by 25-hydroxyvitamin D, since 25-hydroxyvitamin D negatively correlated with parathyroid hormone, which in turn was positively related to RANKL.
  
  
  CONCLUSIONS
  Serum 25-hydroxyvitamin D is inversely correlated with markers of inflammation and may suppress osteoclastic activity in hemodialysis patients.
authors.affiliation: Nephrology Department, Medical School, University of Thessaly, Larissa, Greece. teleftheriadis@yahoo.com
authors.forename: Theodoros
authors.initials: T
authors.lastname: Eleftheriadis
authors.forename: Georgia
authors.initials: G
authors.lastname: Antoniadi
authors.forename: Vassilios
authors.initials: V
authors.lastname: Liakopoulos
authors.forename: Ioannis
authors.initials: I
authors.lastname: Stefanidis
authors.forename: Grammati
authors.initials: G
authors.lastname: Galaktidou
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D001862:Bone Resorption / Q000378:metabolism*; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D006801:Humans; D007249:Inflammation / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D007676:Kidney Failure, Chronic / Q000097:blood / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010010:Osteoclasts; D053244:Osteoprotegerin / Q000378:metabolism; D010281:Parathyroid Hormone / Q000378:metabolism; D053245:RANK Ligand / Q000378:metabolism; D006435:Renal Dialysis; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D015850:Interleukin-6; D053244:Osteoprotegerin; D010281:Parathyroid Hormone; D053245:RANK Ligand; D014807:Vitamin D; D002097:C-Reactive Protein; C104450:25-hydroxyvitamin D