Calcium-Regulating Hormones: General

Several hormones, other than those directly involved in calcium homeostasis (parathyroid hormone, vitamin D, calcitonin), exert effects on bone and calcium metabolism. During the normal growth and development of animals and man, the bones increase in size, change in shape (modelling) and undergo changes in their internal structure and chemical composition. In immature animals, the growth of the skeleton is accompanied by a progressive bodily retention of calcium which extends to the onset of maturity; thereafter bone tissue is lost, especially in women after the menopause. All these changes are brought about by the activity of bone cells (osteoblasts, osteoclasts) and their behaviour is governed by a variety of internal and external factors.