Role of Change in Vitamin D Metabolism with Age in Calcium and Phosphorus Metabolism in Normal Human Subjects*

Abstract

This study describes the age-related changes of vitamin D metabolism and its related hormones, immunoreactive PTH (iPTH) and calcitonin (CT) in normal human subjects. The objective was to assess their roles in the changes in metabolism of calcium and phosphorus with age. Serum calcium and phosphorus levels declined linearly with age from newborn infants to older adults (r = -0.385, P less than 0.01; r = -0.568, P less than 0.01). The serum calcium and phosphorus levels in adults of 51 yr of age or more were significantly lower than those in children and younger adults of 50 yr of age or less (P less than 0.025, P less than 0.01), whereas the calcium and phosphorus levels in cord blood were significantly higher than those in children and younger adults (P less than 0.025, P less than 0.01). The serum concentration of 1 alpha,25-dihydroxyvitamin D (1 alpha,25-(OH)2-Vit D) did not change in children and younger adults, being 42.0 +/- 1.4 (SE) pg/ml, but it significantly decreased to 31.4 +/- 1.9 pg/ml in older adults (P less than 0.01). There were no significant age-related changes in the serum concentrations of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, or vitamin D-binding protein (DBP) among children, younger adults and older adults. The concentrations of all vitamin D metabolites and DBP in cord serum were significantly lower than those in children and younger adults (P less than 0.01). Serum iPTH levels were higher in older adults (P less than 0.05) and lower in cord blood (P less than 0.1), compared with those in children and younger adults, whereas the serum CT level was higher in cord serum (P less than 0.01). No sex differences were found in the serum concentrations of calcium, phosphorus, vitamin D metabolites, DBP, iPTH, and CT. The serum concentration of calcium or phosphorus did not correlate significantly with that of 1 alpha 25-(OH)2-Vit D by simple correlation analysis. Multivariate analysis, however, showed that the change in the serum concentration of 1 alpha,25-(OH)2-Vit D, as well as iPTH and CT, contributed to their correlation with the change in the serum concentrations of calcium and phosphorus. These data indicate that change in vitamin D metabolism might play some role in the age-related change of serum calcium and phosphorus levels in children and adults, but that calcium and phosphorus metabolism in the fetus might be regulated by some mechanisms other than vitamin D metabolism.

Long-Term Treatment Effects of Pueraria mirifica Phytoestrogens on Parathyroid Hormone and Calcium Levels in Aged Menopausal Cynomolgus Monkeys

“…It has been proposed that changes in estradiol levels influence intestinal calcium absorption and increase serum calcium levels as found in healthy humans [26]. However, we did not find the correlation between estradiol levels and PTH levels because of vary estradiol levels.…”

Pharmacokinetics and effects of demographic factors on blood 25(OH)D3 levels after a single orally administered high dose of vitamin D3

“…The basis for such differences is probably due to the decreased capacity of vitamin D absorption and metabolism in elderly subjects. In children and adults, serum calcium and phosphorus levels, but not DBP levels, are higher than those in elderly populations [14] . The major carrier protein for vitamin D metabolites in plasma, DBP, prolongs the half-life for 25(OH)D3 in the blood by acting as a reservoir and promoting the reabsorption of filtered vitamin D in the kidney [15,16] .…”

Vitamin D3 and cardiovascular function in rats.

“…Because only total CPK was measured in the present study, it cannot be said for certain whether the increase in serum CPK in the vitamin D3-deficient rats is due to damage to myocardial or skeletal muscle or both. As (38), and a correlation between increased BP and hypocalcemia has been demonstrated in patients and animal models of hypertension (34). In addition, the possibility exists that vitamin D3 may play a role in the changes in cardiovascular function that can accompany diabetes (39), lengthy bedrest or immobilization (40, 41), or prolonged periods of weightlessness (41), because circulating levels of 1,25(OH)2D3 are reduced by these conditions (42)(43)(44)(45).…”