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 Waller
  • Deborah Ridout
  • Tom Cantor
  • Lesley Rees
Original Article

Abstract

‘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.

Keywords

Immunoradiometric PTH assay Carboxyl-terminal PTH fragments Renal osteodystrophy 

Notes

Acknowledgements

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.

References

  1. 1.
    Goodman WG, Salusky IB, Juppner H (2002) New lessons from old assays: parathyroid hormone (PTH), its receptors, and the potential biological relevance of PTH fragments. Nephrol Dial Transplant 17:1731–1736CrossRefGoogle Scholar
  2. 2.
    John MR, Goodman WG, Gao P, Cantor TL, Salusky IB, Juppner H (1999) A novel immunoradiometric assay detects full-length human PTH but not amino-terminally truncated fragments: implications for PTH measurements in renal failure. J Clin Endocrinol Metab 84:4287–4290CrossRefPubMedGoogle Scholar
  3. 3.
    Tanno Y, Yokoyama K, Nakayama M, Katoh A, Yamamoto H, Iwasaki Y, Cantor T, Fukagawa M, Shigematsu T, Hosoya T (2003) IRMA (whole PTH) is a more useful assay for the effect of PTH on bone than the Allegro intact PTH assay in CAPD patients with low bone turnover marker. Nephrol Dial Transplant 18 [Suppl 3]:97–98Google Scholar
  4. 4.
    Reichel H, Esser A, Roth HJ, Schmidt-Gayk H (2003) Influence of PTH assay methodology on differential diagnosis of renal bone disease. Nephrol Dial Transplant 18:759–768CrossRefGoogle Scholar
  5. 5.
    Goodman WG, Juppner H, Salusky IB, Sherrard DJ (2003) Parathyroid hormone (PTH), PTH-derived peptides, and new PTH assays in renal osteodystrophy. Kidney Int 63:1–11CrossRefGoogle Scholar
  6. 6.
    Brossard JH, Lepage R, Cardinal H, Roy L, Rousseau L, Dorais C, D’Amour P (2000) Influence of glomerular filtration rate on non-(1–84) parathyroid hormone (PTH) detected by intact PTH assays. Clin Chem 46:697–703PubMedGoogle Scholar
  7. 7.
    Waller S, Reynolds A, Ridout D, Cantor T, Gao P, Rees L (2003) Parathyroid hormone and its fragments in children with chronic renal failure. Pediatr Nephrol 18:1242–1248CrossRefGoogle Scholar
  8. 8.
    Salusky IB, Ramirez JA, Oppenheim W, Gales B, Segre GV, Goodman WG (1994) Biochemical markers of renal osteodystrophy in pediatric patients undergoing CAPD/CCPD. Kidney Int 45:253–258PubMedGoogle Scholar
  9. 9.
    Godber IM, Parker CR, Lawson N, Hitch T, Porter CJ, Roe SD, Cassidy MJ, Hosking DJ (2002) Comparison of intact and ‘whole molecule’ parathyroid hormone assays in patients with histologically confirmed post-renal transplant osteodystrophy. Ann Clin Biochem 39:314–317CrossRefGoogle Scholar

Copyright information

© IPNA 2004

Authors and Affiliations

  • Simon Waller
    • 1
    • 4
  • 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

Personalised recommendations