title: An evaluation of 1-84 PTH measurement in relation to bone alkaline phosphatase and bone Gla protein in hemodialysis patients.
abstract: OBJECTIVE
  It has been suggested that higher levels of parathyroid hormone (PTH) are required to maintain normal bone turnover in chronic hemodialysis (HD) patients. Serum PTH levels determined by intact PTH (i-PTH) assay may overestimate the actual activity of circulating PTH in HD patients. The aim of the present study was to assess the clinical usefulness of whole PTH assay on the evaluation of bone turnover in HD patients.
  
  
  METHODS
  We performed measurement of parameters on bone turnover in 179 HD patients (116 men, 63 women; mean age 61.0 +/- 13.1 years). Serum whole PTH levels were determined as cyclase-activating PTH (CAP) by an immunoradiometric assay, and compared with those of i-PTH. Cyclase-inactivating PTH (CIP) was calculated as (i-PTH-CAP). The correlations between serum whole PTH levels and clinical parameters such as serum levels of Ca, P, bone alkaline phosphatase (BAP), bone Gla protein (BGP), total protein (TP), albumin (Alb), urea nitrogen (SUN), and creatinine (Cr) were analyzed using multivariate analysis.
  
  
  RESULTS
  The mean values of i-PTH and CAP were 124.1 +/- 97.4 and 86.9 +/- 71.6 pg/ml, respectively, indicating that the serum CAP levels were about 70% of i-PTH levels. The serum CAP levels significantly correlated with that of i-PTH (r = 0.959, p < 0.001). Moreover, a significant positive correlation between serum CAP levels and metabolic bone markers such as BAP (r = 0.400, p < 0.01) and BGP (r = 0.481, p < 0.01) was observed. Stepwise multivariate analysis revealed that serum levels of CAP were significantly determined by serum levels of Ca, P, Alb, and oral dosage of vitamin D (F ratio = 18.81, adjusted r(2) = 0.302).
  
  
  CONCLUSIONS
  These data suggest that the biological activity of circulating PTH in HD patients is lower than the levels estimated by conventional i-PTH assay.
authors.affiliation: Department of Medicine, Kidney Center, Tokyo Women's Medical University, Shinjuku-ku, Tokyo, Japan. miwa@kc.twmu.ac.jp
authors.forename: Naoko
authors.initials: N
authors.lastname: Miwa
authors.forename: Kosaku
authors.initials: K
authors.lastname: Nitta
authors.forename: Naoki
authors.initials: N
authors.lastname: Kimata
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Koichi
authors.initials: K
authors.lastname: Suzuki
authors.forename: Akira
authors.initials: A
authors.lastname: Kawashima
authors.forename: Masahiro
authors.initials: M
authors.lastname: Haga
authors.forename: Ryo-ichiro
authors.initials: R
authors.lastname: Watanabe
authors.forename: Takanao
authors.initials: T
authors.lastname: Aoki
authors.forename: Takashi
authors.initials: T
authors.lastname: Akiba
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nihei
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D016723:Bone Remodeling / Q000502:physiology; D001842:Bone and Bones / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology; D002118:Calcium / Q000097:blood; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D016326:Extracellular Matrix Proteins; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood; D006435:Renal Dialysis / Q000009:adverse effects; D000097568:Matrix Gla Protein
chemical_list: D000469:Alkaline Phosphatase; D002118:Calcium; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D010281:Parathyroid Hormone; D010758:Phosphorus; D000097568:Matrix Gla Protein