What is the main cause of osteoporosis?

What causes osteoporosis?

Various factors can cause osteoporosis, primarily lack of exercise and a lack of calcium and vitamin D. Smokers are also more affected by osteoporosis. Finally, certain medications and diseases can lead to the development of osteoporosis.

Osteoporosis is a disorder of the bone tissue characterized by a weakening of certain parts of the bones that become fragile and prone to fracture. This disorder affects both men and women of all ages, but particularly older people. Osteoporosis is responsible for many bone fractures in seniors whose weakened bones can no longer support the body’s weight.

Although men are also affected, osteoporosis is most common among women in the menopausal stage. Women are more susceptible to osteoporosis because, after menopause, their ovaries no longer produce the hormone estrogen, which plays a significant role in maintaining a solid female skeleton.

Causes of osteoporosis:

First, it is necessary to mention physicians’ distinction between two forms of osteoporosis: primary and secondary osteoporosis. Primary osteoporosis, which accounts for 95% of cases, occurs without any identifiable cause, whereas secondary osteoporosis, which is much rarer, is caused by pathology.

Factors favoring the development of primary osteoporosis :

-Lack of exercise: Bones are a living tissue that, like muscles, become stronger with practice. Physically active people are less likely to develop osteoporosis because their bones are stronger and more resistant to the effects of aging.

-Calcium deficiency: Calcium and vitamin D play a very important role in maintaining healthy, strong bones throughout life, and therefore in preventing osteoporosis. Vitamin D helps the body absorb more calcium. There is not enough sunlight in Canada to produce enough vitamin D, especially during the winter months, and it is very difficult to get enough vitamin D through diet alone.

-Falling estrogen levels after menopause: Bone loss accelerates dramatically after menopause because the ovaries stop producing estrogen, the hormone that plays a key role in the bone repair process. Female athletes and women with anorexia nervosa may also be at increased risk for osteoporosis. In either case, the menstrual cycle is disrupted or stops, and estrogen levels drop dramatically. Women who undergo menopause early (before age 45) are at increased risk of osteoporosis;

Causes of secondary osteoporosis:

Hormonal system disorders such as:

  • Gonadotropic deficiency (hypogonadism),
  • Excessive functioning of the adrenal glands (hypercorticism),
  • Cushing’s syndrome,
  • Hyperthyroidism,
  • Type 1 and type 2 diabetes:
  • Chronic malnutrition and undernutrition (also in the context of chronic inflammatory bowel disease);
  • Malignant tumors, e.g., bone metastases, bone marrow plasma cell tumor;
  • Rheumatoid arthritis (chronic polyarthritis);
  • Long-term use of certain medications such as steroidal anti-inflammatory;
  • Drugs or heparin;
  • Prolonged immobilization (bed rest).

Both forms of osteoporosis affect men and women equally. Everyone’s risk of developing osteoporosis increases with age, but men are often affected later in life (see Facts about Osteoporosis in Women and Men). Most men with osteoporosis have secondary osteoporosis.

Risk factors for osteoporosis:

Risk factors are all the elements that favor the development of a disease. Some of them cannot be modified. These are called non-modifiable risk factors. They include, among others, family history, age, and gender. Other factors can be modified. Positive effects on osteoporosis can be achieved, for example, through lifestyle changes.

Non-modifiable risk factors (examples):


The risk of osteoporosis increases markedly with age.


Women are affected by osteoporosis more often and earlier than men;
Proven fractures before the age of 45;
Family history: when parents, brothers, or sisters suffer from osteoporosis;

Type 1 and type 2 diabetes;

Chronic inflammatory joint disease (chronic polyarthritis);
Chronic inflammatory bowel disease (e.g., Crohn’s disease).

Modifiable risk factors (examples):

-A diet low in calcium;
-Vitamin D deficiency;
-Underweight: body mass index (BMI) < 20;
-Lack of estrogen: premature menopause (< 42 years);
-Gonadotropic deficiency (hypogonadism);
-Lack of exercise;
-Excessive alcohol and nicotine consumption;
-Certain medications;
-Medications as risk factors for osteoporosis.

Many medications can have a negative effect on bone health, especially when taken in high doses or over the long term. It is important to talk to your doctor about this at your next visit and not to stop or change any medication without his or her approval.

The following drugs may have a negative effect on bone metabolism:

-Glucocorticoids (cortisone),
-Long-term heparin treatment (used in the prevention and treatment of thrombosis),
-GnRH activators (treatment of prostate cancer),
-Anti-androgen therapy (treatment of prostate cancer)
-Aromatase inhibitor (breast cancer treatment),
-Proton pump inhibitors and aluminum-containing antacids for their gastric Protective effect (in case of heartburn and acid regurgitation),
-Anti-epileptic drugs,
-Immunosuppressive drugs (after a transplant),
-Thyroid hormones in large quantities.