Improved assessment of bone turnover by the PTH-(1-84)/large C-PTH fragments ratio in ESRD patients

Marie Claude Monier-Faugere, Zhaopo Geng, Hanna Mawad, Robert M. Friedler, Ping Gao, Tom L. Cantor, Hartmut H. Malluche

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245 Citations (SciVal)

Abstract

Background: The "intact" parathyroid hormone (PTH) assay recognizes PTH-(1-84) as well as amino terminally truncated PTH fragments, that is, large carboxyterminal PTH fragments (C-PTH fragments). The present study investigated whether the use of the plasma PTH-(1-84)/C-PTH fragment ratio enhances the noninvasive assessment of bone turnover in patients on dialysis. Methods: Bone biopsies and blood samples for determinations of routine indices of bone turnover and PTH peptides were obtained in 51 adult patients on dialysis not treated with drugs affecting bone such as vitamin D or corticosteroids. Blood levels of large C-PTH fragments were calculated by subtracting PTH-(1-84) from "intact" PTH. Patients were classified according to their levels of bone turnover based on histo-morphometrically obtained results of activation frequency. Prediction of bone turnover by the various blood indices was done by using proper statistical methods. In addition, hypercalcemia was induced by calcium gluconate infusion in a subset of patients, and levels of PTH-(1-84), "intact" PTH, and PTH-(1-84)/C-PTH fragment ratio were determined. Results: The PTH-(1-84)/C-PTH fragment ratio was the best predictor of bone turnover. A ratio >1 predicted high or normal bone turnover (sensitivity 100%), whereas a ratio <1 indicated a high probability (sensitivity 87.5%) of low bone turn-over. Calcium infusion resulted in decrease in PTH-(1-84)/C-PTH fragment ratio. Conclusions: The PTH-(1-84)/C-PTH fragment ratio predicts bone turnover with acceptable precision for biological measurements. Moreover, a change in serum calcium levels is one of the regulators of the relative amount of circulating PTH-(1-84) and its large C-PTH fragments.

Original languageEnglish
Pages (from-to)1460-1468
Number of pages9
JournalKidney International
Volume60
Issue number4
DOIs
StatePublished - 2001

Bibliographical note

Funding Information:
The study was supported in part from the National Institutes of Health DK 51530 and MO1 RR02602 and the Dialysis Clinics, Inc. This work was presented, in part, at the American Society for Nephrology, Toronto, 2000. We are indebted to Ms. Cindy Molinari, Mr. Richard Wheaton, and Ms. Terri Sexton for their clinical and technical support, and Ms. Louise Tipton for her editorial efforts.

Keywords

  • Carboxyterminal PTH fragments
  • Dialysis
  • Hormone radioimmunoassay
  • Hypercalcemia
  • Intact parathyroid hormone
  • Renal osteodystrophy
  • Secondary hyperparathyroidism

ASJC Scopus subject areas

  • Nephrology

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