Calciotropic hormones and ageing

Calcium availability is reduced in the elderly because not only of decreased dietary intake of calcium and vitamin D, but also reduced solar exposure and a decrease in the production of provitamin D by the skin. Moreover, calcitriol synthesis and calcitriol activity on calcium absorption by the small intestine are decreased with ageing. The age-related plasma parathormone increase enhances bone remodelling. The decrease of calcitonin secretion in the elderly is possibly related to a loss of sex steroids and calcitriol. 24-hour integrated growth hormone (GH) and insulin-like growth factor I concentrations are also decreased with ageing, but the effectiveness of GH therapy on bone mass in the elderly is still assumed.