Aging alters calcium regulation of serum concentration of p
arathyroid hormone in healthy men.
Portale, Anthony A., Edmund T. Lonergan, Diana M. Tanney, and Bernard
P. Halloran.
Departments of Pediatrics and Medicine, The General Clinical
Research Center, University of California and Veterans Affairs
Medical Center, San Francisco, CA. 94143
APStracts 3:0199E, 1996.
We examined the effect of aging on the relationship between the
concentrations of blood ionized calcium and serum PTH, in 22 healthy
men, 9 elderly (age 74+/-2 yrs) and 13 young (age 39+/-1 yrs), in
whom the GFR was >70 ml/min. Throughout a 24 hour period,
serum concentrations of PTH in the elderly men were were twice those
in the young men, whereas blood ionized calcium did not differ
between the two groups. With intravenous infusion of calcium
gluconate, the minimum PTH concentration was significantly higher in
the elderly men. With infusion of NaEDTA, the maximum PTH
concentration was 20% higher in the elderly men. The calcium set
-point for PTH release was higher in the elderly than in the young men
(4.71 + 0.04 vs 4.54 + 0.03 mg/dl, respectively, P<0.005). In
these healthy men, the age-related increase in serum PTH could not be
attributed to a sustained decrease in concentration of either blood
ionized calcium or 1,25(OH)2D. These findings suggest that in the
aging parathyroid gland, the relationship between calcium and PTH is
altered such that at any given level of calcium, the concentration of
PTH is higher.
Received 15 April 1996; accepted in final form 17 September 1996.
APS Manuscript Number E184-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996