Abstract
Measurements of bone mineral content (BMC), intestinal 47Ca absorption, calcium regulating hormones, sex hormones and other hormones were performed on 32 healthy aged subjects (60y.o-85y.o) and 26 controls (15y.o-42y.o).
In BMC, there was a progressive fall after age 40 in both sexes, with the rate of decrease being greater in women than in men, so that at age 70-80, BMC was only 70% of that seen at age 40 in males and 50% in females.
There was a significant correlation between BMC and plasma testosterone levels in the men and between plasma estrogens and BMC in the women, suggesting that testosterone might play an important role in maintaining bone remodeling at the normal rate in males, whereas estrogens were important in females.
Plasma PTH showed no change with age and sex. However, response of the parathyroid to EDTA infusion was significantly lower in the aged females than that seen in the aged males and the controls, indicating that the aged females were in an occult hypoparathyroid state. Basal plasma calcitonin levels were lower in the aged of both sexes than those in the controls. Response of C-cell to Ca infusion was also low, indicating that the C-cells function was reduced in the aged subjects.
Plasma 1,25(OH)2D was reduced in the aged subjects, while plasma 25(OH)D levels were slightly high. It was speculated that the decrease in the conversion of 25-OH-D3 to 1,25(OH)2D3 might be an important factor in causing a decrease in the rate of mineral turnover in bone with age.
In conclusion : aging and calcium metabolism is characterized by a chronic negative imbalance. This negative balance could be a reflection of a hormonal imbalance occurring with aging, and it would become more important to define these changes in order to devise both therapeutic and preventive measures.
