Osteoporosis can be divided into three categories: primary osteoporosis, which is a physiological degenerative disease that occurs with age. Type Ι is postmenopausal osteoporosis, which occurs in postmenopausal women between the ages of 51 and 75, but may occur earlier or later. Type Π is senile osteoporosis, which may be related to insufficient calcium intake, unbalanced rate of bone destruction and new bone formation. It mostly occurs after the age of 65. Long-term alcohol consumption, smoking, insufficient calcium intake in the diet and lack of outdoor activities are more likely to cause osteoporosis. The second category is secondary osteoporosis, which is osteoporosis caused by other diseases or drugs. Examples include chronic renal failure, endocrine disorders (especially thyroid, parathyroid or adrenal disorders, diabetes) and medications (e.g., corticosteroids, barbiturates, anticonvulsants, and overdose of thyroxine). The third category is idiopathic osteoporosis, which occurs in adolescents or adults aged 8 to 14 years, many with a genetic family history and more women than men. Women with osteoporosis during pregnancy and lactation can also be included in idiopathic osteoporosis.