title: Parathormone and bone-specific alkaline phosphatase for the follow-up of bone turnover in hemodialysis patients: is it so simple?
abstract: BACKGROUND
  Chronic Kidney Disease (CKD) is associated with mineral and bone disorders (MBD). International guidelines suggest that levels of serum parathormone (PTH) or bone-specific alkaline phosphatase (b-ALP) can be used to evaluate MBD in dialysis patients. The evidence remains moderate and based on transversal studies.
  
  
  METHODS
  We retrospectively investigated the variations of PTH (ΔPTH) and b-ALP (Δb-ALP) serum concentrations over a short (6-weeks) and a long (one-year) period in a monocentric hemodialysis population. The proportion of patients reaching the critical difference (CD) (50% for PTH and 25% for b-ALP) was calculated.
  
  
  RESULTS
  Seventy-seven patients were included. A significant correlation between PTH and b-ALP levels was found at baseline (r=0.51). By contrast, no correlation was observed between ΔPTH and Δb-ALP over a 6-week interval (r=0.07). The CD for PTH and b-ALP was reached by 19 and 11 patients, respectively, with 2 patients showing consistent variations of both biomarkers. One year later, measurements were repeated in 48 survivors. No correlation was found between ΔPTH and Δb-ALP (r=0.27). The CD for PTH or b-ALP was reached by 24 patients and 28 patients, respectively, with 6 patients (12.5%) showing opposite results for both biomarkers.
  
  
  CONCLUSIONS
  This study shows the lack of correlation between ΔPTH and Δb-ALP over time in patients under chronic hemodialysis.
authors.affiliation: Division of Nephrology-Dialysis-Hypertension, University of Liège, CHU Sart Tilman, Liège, Belgium. pierre_delanaye@yahoo.fr
authors.forename: Pierre
authors.initials: P
authors.lastname: Delanaye
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Dubois
authors.forename: François
authors.initials: F
authors.lastname: Jouret
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Krzesinski
authors.forename: Olivier
authors.initials: O
authors.lastname: Moranne
authors.forename: Etienne
authors.initials: E
authors.lastname: Cavalier
mesh_terms: D000368:Aged; D000469:Alkaline Phosphatase / Q000378:metabolism*; D016723:Bone Remodeling; D001842:Bone and Bones / Q000201:enzymology* / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009928:Organ Specificity; D010281:Parathyroid Hormone / Q000097:blood*; D006435:Renal Dialysis; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000201:enzymology / Q000503:physiopathology / Q000628:therapy; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone; D000469:Alkaline Phosphatase