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Acute changes in serum osteocalcin during induced hypocalcemia in humans
C M Gundberg1, F D Grant, P R Conlin
1Department of Orthopaedics, Yale University School of Medicine, New Haven, Connecticut 06115.
The Journal of Clinical Endocrinology and Metabolism
|February 1, 1991
Summary
Serum osteocalcin levels, an indicator of bone formation, are acutely influenced by rapid changes in ionized calcium (CaI) and parathyroid hormone (PTH). Faster CaI decreases led to significant osteocalcin increases, suggesting rapid regulation.
Area of Science:
- Endocrinology
- Bone Metabolism
- Calcium Homeostasis
Background:
- Serum osteocalcin is a marker for osteoblastic activity and bone formation.
- Limited data exists on the acute impact of calcium and parathyroid hormone (PTH) on circulating osteocalcin.
Purpose of the Study:
- To investigate the acute effects of stepwise decreases in ionized calcium (CaI) on serum osteocalcin concentrations.
- To determine the relationship between CaI, PTH, and osteocalcin levels under different infusion rates.
Main Methods:
- Six healthy subjects received citrate infusions over four 30-min intervals using pulse and continuous infusion protocols.
- Serum ionized calcium (CaI), intact PTH, and osteocalcin levels were monitored throughout the infusions.
Main Results:
- During pulse infusion, osteocalcin changes paralleled PTH (r=0.462, P=0.02) and inversely correlated with CaI (r=-0.562, P=0.003).
- Osteocalcin levels significantly increased from 3.46 ± 0.63 to 6.88 ± 1.08 µg/L (P<0.05) during pulse infusion.
- Continuous infusion showed a delayed osteocalcin response, with significant changes only in the latter two periods.
Conclusions:
- Circulating osteocalcin concentrations appear to be acutely regulated by calcium and/or PTH.
- The rate of change in CaI significantly influences the acute osteocalcin response.