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[PTH and bone metabolism in chronic dialysis patients]
M Fukagawa1, J Kazama, T Shigematsu
1Division of Nephrology and Dialysis Center, Kobe University School of Medicine, Kobe 650-0017.
Insights
Chronic dialysis patients often have abnormal calcium and bone metabolism. Intact parathyroid hormone (PTH) assays may overestimate activity, and osteoprotegerin may cause skeletal resistance to PTH in uremia.
Area of Science:
- Nephrology
- Endocrinology
- Bone Metabolism
Background:
- Abnormal calcium and bone metabolism is a frequent complication in chronic dialysis patients.
- Intact parathyroid hormone (PTH) assays may overestimate PTH activity by including inactive fragments.
- Uremic patients may require higher PTH levels for normal bone turnover, suggesting skeletal resistance.
Purpose of the Study:
- To investigate the accuracy of intact PTH assays in chronic dialysis patients.
- To explore the role of PTH fragments and osteoprotegerin in uremic bone disease.
Main Methods:
- Analysis of PTH activity using intact PTH assays.
- Assessment of PTH fragments (e.g., 7-84 PTH) and whole PTH (1-84 PTH).
- Evaluation of osteoprotegerin levels in uremic serum.
Main Results:
- Intact PTH assays may overestimate parathyroid hormone activity.
- Accumulated osteoprotegerin in uremic serum might contribute to skeletal resistance to PTH.
- Higher PTH levels are needed to maintain bone turnover in uremic patients.
Conclusions:
- The accuracy of intact PTH assays in dialysis patients needs further validation.
- Osteoprotegerin may play a significant role in the pathogenesis of uremic bone disease.
- Understanding these factors is crucial for managing bone complications in chronic kidney disease.
Abstract:
The abnormal metabolism of calcium and bone is one of the most common complications seen in chronic dialysis patients. The activity of PTH has been mainly assessed by intact PTH assay; however, recent data suggest that this assay may overestimate PTH activity by detecting 7-84 PTH fragments in addition to 1-84 PTH molecules(whole PTH). Another issue in this field is that higher levels of PTH are needed to maintain normal bone turnover in uremic patients. Accumulated osteoprotegerin in uremic serum may be responsible for this skeletal resistance to PTH.