title: Maxacalcitol therapy decreases circulating osteoprotegerin levels in dialysis patients with secondary hyperparathyroidism.
abstract: BACKGROUND
  Osteoprotegerin is a natural glycoprotein which plays a critical role in osteoclast physiology. Elevated levels of circulating osteoprotegerin may account for the development of bone and mineral metabolic abnormalities in uremia. Little is known about the effects of vitamin D therapy on the circulating osteoprotegerin levels in dialysis patients.
  
  
  METHODS
  Fifty chronic dialysis patients whose plasma intact PTH levels were greater than 300 pg/ml were analyzed for the study. Following a four-week washout time during which all vitamin D administration was halted, 10 microg of maxacalcitol was intravenously injected thrice a week.
  
  
  RESULTS
  The circulating intact PTH, bone-specific alkaline phosphatase and intact osteocalcin levels were significantly lowered, while the serum calcium levels were elevated after the therapy. The osteoprotegerin levels significantly decreased after the therapy (p < 0.0001).
  
  
  CONCLUSIONS
  Maxacalcitol therapy reduced the circulating osteoprotegerin levels and improved secondary hyperparathyroidism. The observed effects were the opposite of those expected from previous in vitro studies. Osteoprotegerin may mediate and/or modify the effect of active vitamin D therapy in dialysis patients.
authors.affiliation: Division of Clinical Nephrology and Rheumatology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan. jjkaz@med.niigata-u.ac.jp
authors.forename: J J
authors.initials: JJ
authors.lastname: Kazama
authors.forename: K
authors.initials: K
authors.lastname: Omori
authors.forename: N
authors.initials: N
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: H
authors.initials: H
authors.lastname: Maruyama
authors.forename: I
authors.initials: I
authors.lastname: Narita
authors.forename: F
authors.initials: F
authors.lastname: Gejyo
authors.forename: Y
authors.initials: Y
authors.lastname: Iwasaki
authors.forename: M
authors.initials: M
authors.lastname: Fukagawa
mesh_terms: D002117:Calcitriol / Q000031:analogs & derivatives* / Q000627:therapeutic use; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D053244:Osteoprotegerin; D010281:Parathyroid Hormone / Q000097:blood; D018160:Receptors, Cytoplasmic and Nuclear / Q000097:blood*; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood*; D006435:Renal Dialysis; D018709:Statistics, Nonparametric; D016896:Treatment Outcome
chemical_list: D006023:Glycoproteins; D053244:Osteoprotegerin; D010281:Parathyroid Hormone; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506030:TNFRSF11B protein, human; D002117:Calcitriol; C051883:maxacalcitol