title: Microscopic nephrocalcinosis in chronic kidney disease patients.
abstract: BACKGROUND
  Experimental data indicate that microscopic calcium phosphate deposition in the kidney (nephrocalcinosis) may accelerate progression of chronic kidney disease (CKD). Data on the prevalence, risk factors and implications of nephrocalcinosis in CKD patients are scarce. A mineral metabolism disorder could play an important pathogenetic role, as suggested by recent protocol biopsy findings in incident renal transplant recipients.
  
  
  METHODS
  Kidney biopsy cylinders of CKD patients, collected between January 1989 and December 2007, were screened for the presence of nephrocalcinosis. Only patients with ≥1 parathyroid hormone (PTH) level available within 180 days of the biopsy were eligible for inclusion (n = 211). Demographics and mineral metabolism parameters were retrieved from medical files. Data on renal death (up to December 2012) were obtained from the Flemish ESRD registry. Baseline biopsies from 110 deceased kidney transplant donors served as controls.
  
  
  RESULTS
  The prevalence of nephrocalcinosis in kidney donors and patients with CKD 1-2, CKD 3-4 and CKD 5-5D was 4.6, 14.3, 20.2 and 54.0%, respectively (P < 0.0001). Among CKD patients, patients with nephrocalcinosis were characterized by lower estimated GFR, lower serum bicarbonate level and higher serum PTH and calcium level. In multivariate regression analysis, high serum PTH, calcium and creatinine level, and low serum bicarbonate level were all significantly and independently associated with nephrocalcinosis. Serum phosphorus level, but not nephrocalcinosis predicted renal death, independent of renal function.
  
  
  CONCLUSIONS
  Our data demonstrate that prevalence rates of nephrocalcinosis increase with increasing CKD stage to reach more than 50% in end-stage renal disease patients and suggest that acid-base and mineral metabolism disturbances are implicated in its pathogenesis.
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Evenepoel
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Kristien
authors.initials: K
authors.lastname: Daenen
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Bert
authors.initials: B
authors.lastname: Bammens
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Claes
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Björn
authors.initials: B
authors.lastname: Meijers
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Naesens
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Ben
authors.initials: B
authors.lastname: Sprangers
authors.affiliation: Department of Microbiology and Immunology, Laboratory of Nephrology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Kuypers
authors.affiliation: Department of Pathology, University Hospitals Leuven, Leuven B-3000, Belgium.
authors.forename: Eveline
authors.initials: E
authors.lastname: Lerut
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D002118:Calcium / Q000097:blood; D003404:Creatinine / Q000097:blood; D018450:Disease Progression; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009397:Nephrocalcinosis / Q000150:complications* / Q000453:epidemiology; D010281:Parathyroid Hormone / Q000097:blood*; D010710:Phosphates / Q000097:blood; D015995:Prevalence; D012042:Registries; D051436:Renal Insufficiency, Chronic / Q000150:complications* / Q000453:epidemiology; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D003404:Creatinine; D002118:Calcium
keywords: CKD-MBD; nephrocalcinosis