Pediatric Nephrology

, Volume 20, Issue 2, pp 197–199 | Cite as

Differences between ‘intact’ PTH and 1–84 PTH assays in chronic renal failure and dialysis

  • Simon WallerEmail author
  • Deborah Ridout
  • Tom Cantor
  • Lesley Rees
Original Article


‘Intact’ parathyroid hormone (iPTH) assays overestimate actual PTH as they cross-react with non (1–84) PTH fragments (C-PTH) that accumulate in renal failure. New assays that measure just 1–84 PTH (CAP-PTH) are now available. It has been suggested that there is a linear relationship between the two assays; however, increased C-PTH levels are found as glomerular filtration rate (GFR) declines and in patients on dialysis. We investigated the relationship between iPTH and CAP-PTH in children with chronic renal failure (CRF) managed conservatively and on dialysis. We investigated 241 children, 156 with a GFR <60 ml/min per 1.73 m2 managed conservatively, 49 post renal transplant (and GFR <60 ml/min per 1.73 m2) and 36 on dialysis, by measuring PTH levels by iPTH and CAP-PTH assays. Multiple regression analysis comparing differences between PTH levels in each patient group was performed. Correlation slopes between iPTH and CAP-PTH assays differed between CRF and dialysis patients (P=0.001). These assays perform differently in CRF and dialysis patient groups. Studies investigating the correlation between newer assays and bone histology are required to determine whether these more-specific PTH assays are superior surrogate markers of bone turnover.


Immunoradiometric PTH assay Carboxyl-terminal PTH fragments Renal osteodystrophy 



This work was supported by grants from the National Kidney Research Fund (R 18/2/2001), Renal Care and Research Association and the Special Trustees of Great Ormond Street Hospital.


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Copyright information

© IPNA 2004

Authors and Affiliations

  • Simon Waller
    • 1
    • 4
    Email author
  • Deborah Ridout
    • 2
  • Tom Cantor
    • 3
  • Lesley Rees
    • 1
  1. 1.Department of Nephro-UrologyInstitute of Child Health and Great Ormond Street Hospital for Children NHS TrustLondonUK
  2. 2.Department of Paediatric Epidemiology and Biostatistics UnitInstitute of Child Health and Great Ormond Street Hospital for Children NHS TrustLondonUK
  3. 3.Scantibodies LaboratoriesSanteeUSA
  4. 4.Renal OfficesGreat Ormond Street Hospital for Children NHS TrustLondonUK

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