title: Mineral metabolism parameters throughout chronic kidney disease stages 1-5--achievement of K/DOQI target ranges.
abstract: BACKGROUND
  Dialysis Outcomes and Practice Patterns Study has shown that the proportion of haemodialysis patients with adequate mineral metabolism parameters according to the Kidney Disease Outcome Quality Initiative (K/DOQI) guidelines is very low. The adequacy of such parameters in relation to the recommended ranges in patients with different chronic kidney disease (CKD) stages has not been reported. The objective of this study is to provide an in-depth description of mineral metabolism in the early stages of CKD in a European population, and to compare it with current recommendations for stages 3-5 (K/DOQI guidelines).
  
  
  METHODS
  A total of 1836 patients were classified into stages 1-5 according to K/DOQI guidelines. The following clinical and biochemical data were recorded: age, gender, CKD aetiology, presence of diabetes, serum creatinine, creatinine clearance, serum phosphate, calcium, CaxP product and intact parathyroid hormone (PTH).
  
  
  RESULTS
  A decrease in 1,25-dihydroxyvitamin D and an increase in PTH are the earliest mineral metabolism alterations in CKD, while serum calcium and phosphate are altered later in the course of CKD. The percentages of patients with serum levels within the recommended K/DOQI guidelines for stages 3, 4 and 5 were as follows: serum calcium: 90.7, 85.6 and 55; serum phosphate: 90.9, 77.1 and 70.3; iPTH 42.4, 24.6 and 46.8 and Ca x P product 99.9, 99.6 and 83.8, respectively. The percentages of patients who had all four parameters within the recommended ranges were 34.9, 18.4 and 21.6 for stages 3, 4 and 5, respectively.
  
  
  CONCLUSIONS
  Mineral metabolism disturbances start early in the course of CKD. The first alterations to take place are a 1,25-dihydroxyvitamin D decrease, a 24 h urine phosphate decrease and a PTH elevation, which show significant level variation when the glomerular filtration rate falls below 60 ml/min. K/DOQI recommended levels for mineral metabolism parameters are difficult to accomplish, in particular for PTH levels.
authors.affiliation: Hospital Universitari Arnau de Vilanova, Av Rovira Roure, 25198 Lleida, Spain. lcraver@arnau.scs.es
authors.forename: Lourdes
authors.initials: L
authors.lastname: Craver
authors.forename: Maria Paz
authors.initials: MP
authors.lastname: Marco
authors.forename: Isabel
authors.initials: I
authors.lastname: Martínez
authors.forename: Montserrat
authors.initials: M
authors.lastname: Rue
authors.forename: Merce
authors.initials: M
authors.lastname: Borràs
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Martín
authors.forename: Felipe
authors.initials: F
authors.lastname: Sarró
authors.forename: José Manuel
authors.initials: JM
authors.lastname: Valdivielso
authors.forename: Elvira
authors.initials: E
authors.lastname: Fernández
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002118:Calcium / Q000097:blood; D002908:Chronic Disease; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D005060:Europe; D005260:Female; D006801:Humans; D007674:Kidney Diseases / Q000208:ethnology / Q000378:metabolism* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D008903:Minerals / Q000378:metabolism*; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data*; D010281:Parathyroid Hormone / Q000097:blood; D010710:Phosphates / Q000097:blood; D017410:Practice Guidelines as Topic; D012016:Reference Values; D006435:Renal Dialysis; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood
chemical_list: D008903:Minerals; D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D; D003404:Creatinine; D002118:Calcium