Osteoporosis causes the loss of bone mineral density (BMD) that results in weak, brittle bones and can lead to painful and debilitating fractures. In most people, a combination of inherited genetic and environmental risk factors contribute to the development of osteoporosis (primary osteoporosis). In others, osteoporosis is caused directly by another health condition or a medication (secondary osteoporosis). Read more about types of osteoporosis.

Age is the biggest risk factor for osteoporosis in all people. Risk begins to rise after age 50. For women, lower levels of hormones after menopause add to the risk for developing osteoporosis.

Risk Factors for Osteoporosis

It is important to note that while science is good at finding correlations, or apparent relationships, between factors and disease, correlation does not prove that the factor causes the disease. Many risk factors for osteoporosis are still being studied.

Hereditary Factors

The tendency to develop osteoporosis runs in families. Researchers have identified several genetic variants that influence bone mineral density (BMD). Scientists estimate that inherited genetic makeup may determine as much as 75 percent of peak BMD. BMD peaks around age 30, and a higher peak BMD is protective against osteoporosis. Those with a family history of osteoporosis – especially those with a parent who have broken a hip – are encouraged to seek early screening for osteoporosis.

As many as half of women and one-quarter of men over 50 have osteoporosis. Women’s higher rates of osteoporosis are partly due to their smaller frames – thinner bones are more quickly affected by bone loss – and by the drop in estrogen and other hormones that protect bones after menopause.

Approximately 5 percent of women go through early menopause. Early menopause (between ages 40 and 45) tends to run in families.

Ethnicity may influence osteoporosis predisposition. Women of Asian and European descent seem to develop osteoporosis at higher rates than women of other ethnic backgrounds.

Environmental Factors

Researchers have identified many environmental factors linked to the development of osteoporosis.

Diet can be a contributing factor in osteoporosis. Calcium and vitamin D are vital for building strong bones. People who do not get enough of these nutrients in their diets, or did not get enough during their early adulthood while building their bone mass, are at greater risk for osteoporosis. Diets excessively high in protein or sodium can cause the body to lose calcium, making it harder for the body to build strong bones.

A sedentary lifestyle with too little exercise can promote loss of bone mineral density. Being sedentary during early adulthood can result in a lower peak bone mineral density and a higher risk for later osteoporosis.

Several studies have shown evidence that heavy smoking reduces bone mass. Likewise, researchers have proven a strong link between chronic, heavy alcohol drinking – especially during adolescence and young adulthood – and lowered measures of bone density. Beverages containing caffeine are also thought to decrease calcium absorption and contribute to bone loss.

Exposure to the toxic metal cadmium is believed to contribute to the development of osteoporosis. Cadmium is a pollutant present in some water, soil, and plant fertilizer. People are exposed when they smoke tobacco or eat vegetables grown in polluted conditions. Welders and workers in fields such as textiles, plastics, or battery manufacturing may be exposed to cadmium on the job.

Oophorectomy (surgical removal of the ovaries) before age 45 causes menopause. The drop in estrogen contributes to a loss of bone mineral density.

Obesity is a protective factor that lowers the risk for osteoporosis, while losing weight can raise the risk for osteoporosis. It is theorized that carrying extra weight may have a similar effect as exercise in increasing bone mineral density, or that fat cells release estrogen – a hormone that reduces the breakdown of bone.

Which Health Conditions Can Cause Osteoporosis?

A large number of diseases can cause the loss of bone mineral density that leads to osteoporosis. Some conditions affect the hormones that regulate bone building, while others make it difficult for the body to absorb or use calcium or other nutrients vital for health bones.

Conditions that can cause secondary osteoporosis include:

• Anorexia nervosa
• Bulimia
• Celiac disease
• Chronic obstructive pulmonary disease (COPD)
• Cushing's disease
• Diabetes
• Kidney failure
• Leukemia
• Liver disease
• Multiple myeloma
• Multiple sclerosis
• Overactive parathyroid gland
• Overactive thyroid gland
• Rheumatoid arthritis

Which Medications Can Cause Osteoporosis?

Some medications that affect hormone levels or the absorption of nutrients in the digestive system can promote the development of osteoporosis.

Drugs known to cause osteoporosis in some people include:

• Anti-seizure drugs including Tegretol (Carbamazepine) and Dilantin (Phenytoin)
• Breast cancer drugs such as Arimidex (Anastrozole), Femara (Letrozole), and Aromasin (Exemestane)
• Corticosteroids such as Prednisone, Dexamethasone, or Methylprednisolone
• Depo-Provera (Medroxyprogesterone)
• Diuretics (“water pills”) such as Lasix (Furosemide)
• Flomax (Tamsulosin) and other drugs for benign prostatic hyperplasia
• Prostate cancer treatment that suppresses male sex hormones
• Proton pump inhibitors such as Prevacid (Lansoprazole) and Nexium (Esomeprazole)
• Some medications for hypertension (high blood pressure)
• Thyroid hormone replacement (at excessive doses)

Condition Guide

• Osteoporosis – An Overview
• Osteoporosis Symptoms
• Osteoporosis – The Path to Diagnosis
• Osteoporosis Treatment
• Types of Osteoporosis