title: Circulating levels of osteoprotegerin and receptor activator of NF-kappaB ligand in patients with chronic renal failure.
abstract: BACKGROUND
  Osteoprotegerin (OPG) is a recently identified cytokine that acts as a decoy receptor for the receptor activator of nuclear factor-kappaB ligand (RANKL). OPG and RANKL have been shown to be important regulators of osteoclastogenesis. The aim of this study was to investigate the relationship between the OPG-RANKL system and bone mineral metabolism in patients with chronic renal failure (CRF).
  
  
  METHODS
  Serum OPG, RANKL, osteocalcin, cross-linked c-telopeptide of type I collagen (ICTP), intact parathyroid hormone (PTH), bone alkaline phosphatase and cystatin C levels were measured in 40 chronic hemodialysis male patients and 32 age- and sex-matched healthy controls. Their lumbar spine bone mineral density (LS-BMD) was measured by dual energy X-ray absorptiometry.
  
  
  RESULTS
  Serum OPG, RANKL, PTH, bone alkaline phosphatase and cystatin C levels were significantly increased in patients with CRF. Serum OPG was positively correlated to serum RANKL and cystatin C. Positive correlations were found between serum RANKL and cystatin C and ICTP. LS-BMD was significantly lower in patients with CRF than in controls. In patients with CRF, LS-BMD was inversely correlated to serum RANKL and cystatin C, whereas it was positively correlated to serum OPG.
  
  
  CONCLUSIONS
  The OPG-RANKL system is involved in the pathogenesis and regulation of bone turnover in CRF. Circulating levels of OPG and RANKL may be useful markers to assess turnover renal osteopathies.
authors.affiliation: Endocrinology and Maternal Biochemistry Labs, Department of Obstetrics and Gynecology, Faculty of Medicine, Cairo University, Cairo, Egypt. mohamedshaarawy@yahoo.com
authors.forename: Mohamed
authors.initials: M
authors.lastname: Shaarawy
authors.forename: Shadia A
authors.initials: SA
authors.lastname: Fathy
authors.forename: Nagy L
authors.initials: NL
authors.lastname: Mehany
authors.forename: Odette W
authors.initials: OW
authors.lastname: Hindy
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D015519:Bone Density; D055316:Cystatin C; D015891:Cystatins / Q000097:blood; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000503:physiopathology; D008024:Ligands; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D053244:Osteoprotegerin / Q000097:blood*; D053245:RANK Ligand / Q000097:blood*
chemical_list: D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins; D008024:Ligands; D053244:Osteoprotegerin; D053245:RANK Ligand; C505688:TNFSF11 protein, human; D015675:Osteocalcin