Review of Medical Physiology - William F. Ganong 2002

Endocrine System, Metabolism, and Reproduction
Hormonal Regulation of Calcium Metabolism and Bone Physiology
Effects of Other Hormones and Humoral Agents on Calcium Metabolism

Calcium METABOLISM is regulated not only by 1,25-dihydroxycholecalciferol, parathyroid hormone, parathyroid hormone-related peptide, and Calcitonin, but also by numerous Other Hormones. Glucocorticoids decrease plasma Ca2+ levels by inhibiting osteoclast formation and activity; prolonged use leads to Osteoporosis due to reduced Bone Formation and increased bone resorption. They decrease bone formation by suppressing Protein Synthesis in osteoblasts, slow down the intestinal absorption of Ca2+ and PO43-, and enhance renal excretion of these ions. Consequently, they counteract hypercalcemia induced by vitamin D toxicity, while the resulting drop in plasma Ca2+ concentration stimulates parathyroid hormone secretion, which further promotes bone resorption.

Growth Hormone promotes urinary calcium excretion, yet it also enhances intestinal calcium absorption—an effect that can outweigh its impact on excretion, resulting in an overall positive calcium balance.

IGF-I, produced in response to growth hormone, stimulates protein synthesis in bone. As noted previously, THYROID HORMONES can induce hypercalcemia, hypercalciuria, and, in some cases, osteoporosis.

Estrogens prevent The Development of osteoporosis, likely through a direct action on osteoblasts (see above).

Insulin promotes bone formation, which explains why untreated diabetes is accompanied by significant bone mass loss.



Last update: 10/08/2026

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