Osteoporosis is a metabolic disease in which bones become fragile and more likely to break. It is often a “silent” disease in that, if not prevented or if left untreated, it progresses painlessly until a bone breaks. There are four types of osteoporosis:

Post-menopausal Osteoporosis (Type 1) occurs in women several years after menopause. After menopause, women's ovaries produce less estrogen. Estrogen is responsible for regulating bone growth and absorption, and therefore bone density decreases. As much as 2-3 percent of overall bone mass can be lost each year, totaling up to 50 percent of bone loss by the age of 70 or 80.

Senile Osteoporosis (Type II) can affect both men and women over the age of 70. Bone mineral density peaks at around the age of 35, and decreases gradually after this. Thus the risks associated with osteoporosis increase with age.

Secondary Osteoporosis describes osteoporosis caused by the use of a drug or as a complication related to another condition such as kidney failure, hyperthyroidism, anorexia, diabetes, rheumatoid arthritis and a number of other illnesses.

Idiopathic Juvenile Osteoporosis is a very rare form of the disease which affects some children or adolescents for no known reason. The disease usually occurs just before puberty.