INCREASES IN IMMUNOREACTIVE PARATHYROID-HORMONE WITH AGE

IN the process of conducting studies to characterize the effects of age on bone mass and the skeleton in adult human subjects, we measured serum immunoreactive parathyroid hormone by a radioimmunoassay that is specific for the biologically inactive carboxylterminal portion of the hormone. We now report that the mean concentration of circulating parathyroid hormone measured by this assay increases with age and that this age-related increase in hormone level is associated with decreases in mean serum ionized calcium and mean serum phosphorus. Methods Normal subjects who ranged in age from 21 to 89 years were studied. The 75 men and. © 1979, Massachusetts Medical Society. All rights reserved.