Osteoporosis :

Definition : It is reduction in bone tissue mass causing weakness of skeletal strength (G. osteon = bone, pros = pore, oisis = condition.)

Factors :

1. Excessive resorption of Ca⁺² from bones : It results from excessive resorption of calcium and phosphorus from the bone, which leads to vertical compression or crush fracture of the vertebrae.

2. Menopause and Ca⁺² absorption : Osteoporosis occurs in postmenopausal women and elderly men. It may result from defective intestinal calcium absorption.

3. Environmental factors : Possible environmental factors include smoking, excessive drinking and decreased exercise. Osteoporosis is more common in women than in men, and in old than middle aged persons.

4. Sex hormones : Imbalances of some hormones, thryocalcitonin, parathormone etc also cause osteoporosis.

5. Vitamin D : Deficiency of vitamin D causes osteoporosis.