title: Clinical evaluation of two novel biointact PTH(1-84) assays in hemodialysis patients.
abstract: OBJECTIVE
  In chronic kidney disease-mineral and bone disorder (CKD-MBD), most treatment decisions are guided by parathyroid hormone (PTH) levels. Here, we aimed at assessing the technical and clinical performance of two novel automated biointact PTH(1-84) assays, from Roche Diagnostics (Ro) and DiaSorin (DS), in hemodialysis patients.
  
  
  METHODS
  We recorded demographics, dialysis treatment characteristics, pharmacotherapy for CKD-MBD and laboratory work-up. Statistical methods included Passing-Bablok, and multiple linear regression.
  
  
  RESULTS
  121 patients, dialyzing on average for 3.5 years (range: 0.1-22.5), with serum phosphate 1.9±0.6 mmol/L (mean±SD), participated in the study. Median serum concentration for intact PTH was 223 ng/L (range: 5-2844), and for biointact PTH(1-84) was 136 ng/L (Ro; range: 1-1644), respectively 138 ng/L (DS; range: 4-1580). Both biointact assays were significantly correlated (r=0.98; Ro=0.87×DS+19.60). Bland-Altmann plots revealed an average bias ±2 SD of 10±27 ng/L below 200 ng/L, and -32±157 ng/L above 200 ng/L (Ro minus DS). The variably adjusted association between PTH and serum phosphate was very similar, regardless of the PTH assay, but this was not the case for PTH-derived measures (ratios biointact/intact; differences intact minus biointact). (Log)PTH concentrations as well as serum phosphate were significantly associated with serum creatinine, but only in patients with >0 mL urine per day.
  
  
  CONCLUSIONS
  Results from Roche and DiaSorin biointact PTH(1-84) assays were well correlated, but showed increased deviations at higher concentrations. Biointact PTH(1-84) levels are roughly two third of intact PTH. The association between PTH and serum creatinine may depend on residual renal clearance of PTH and/or serum phosphate.
authors.affiliation: Medical University of Vienna, Department of Medicine III, Division of Nephrology & Dialysis, Austria. manfred.hecking@meduniwien.ac.at
authors.forename: Manfred
authors.initials: M
authors.lastname: Hecking
authors.forename: Alexander
authors.initials: A
authors.lastname: Kainz
authors.forename: Bernhard
authors.initials: B
authors.lastname: Bielesz
authors.forename: Max
authors.initials: M
authors.lastname: Plischke
authors.forename: Georg
authors.initials: G
authors.lastname: Beilhack
authors.forename: Walter H
authors.initials: WH
authors.lastname: Hörl
authors.forename: Gere
authors.initials: G
authors.lastname: Sunder-Plassmann
authors.forename: Christian
authors.initials: C
authors.lastname: Bieglmayer
mesh_terms: D001681:Biological Assay / Q000379:methods*; D003404:Creatinine / Q000097:blood; D003710:Demography; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000032:analysis*; D010710:Phosphates / Q000097:blood; D006435:Renal Dialysis
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D003404:Creatinine