Skip to content
My WebMD Sign In, Sign Up
Font Size

What Causes Osteoporosis? And Why?

Think you know what causes osteoporosis? Think again -- some of the causes may surprise you.

Causes of Osteoporosis: Other Hormone Imbalances

Several other hormones play a role in regulating your bone density, including parathyroid hormone and growth hormone. They help orchestrate how well your bones use calcium -- and when to build up and break down bone.

But too much parathyroid hormone, called hyperparathyroidism, causes calcium loss in the urine at the expense of bone, says Mystkowski. Less calcium means weaker bones. And as you age, your body produces less growth hormone, which you need to build strong bone.

Causes of Osteoporosis: Lack of Calcium

Without calcium, you can't rebuild new bone during the lifelong process of bone remodeling.

Bones are the reservoir for two minerals -- calcium and phosphorus. You need a constant level of calcium in your blood since many of your organs, especially your heart, muscles, and nerves, depend on calcium. When these organs demand calcium, they'll steal it from the mineral storehouse in your bones. Over time, as you deplete the mineral reservoir in your bones, you end up with thin, brittle bones.

Causes of Osteoporosis: Lack of Vitamin D

Too little vitamin D can lead to weak bones and increased bone loss. Active vitamin D, also called calcitriol, is more like a hormone than a vitamin, says Mystkowski. Among its many benefits, vitamin D helps your body to absorb and use calcium.

Causes of Osteoporosis: A Sedentary Lifestyle

Bones weaken if they aren't worked. Remember the early astronauts? They suffered rapid bone loss from being weightless in space. For people who are sedentary or have a condition like paralysis or muscular dystrophy, bone loss happens quickly. As a cause of osteoporosis, this one's in your hands. You can help "remodel" your bones with weight-bearing exercise, where you're putting gentle stress on bones.

Causes of Osteoporosis: Thyroid Conditions

High levels of thyroid hormone have long been linked to an increase in bone loss. "That's always been a concern of most physicians," says Mystkowski, "but if you look at the long-term bone densities of patients who are on high doses of thyroid pills, they're not dramatically different, and their fracture risk isn't dramatically different."

Still, most doctors would agree: anyone on high doses on thyroid hormone can benefit from getting regular exercise and taking enough calcium and vitamin D. These lifestyle factors are potent ways to manage your overall fracture risk, along with monitoring bone density with testing.

Causes of Osteoporosis: Smoking

Smokers suffer from lower bone density and a higher risk of fracture than non-smokers. Studies on smoking and bone health have turned up a host of other dire effects, from direct toxic effects of nicotine on bone cells to blocking the body's ability to use estrogen, calcium, and vitamin D.

Causes of Osteoporosis: Medications

Taking certain medications may lead to bone loss and an increase in bone fractures. Most common are corticosteroids, also known as cortisone, hydrocortisone, glucocortisoids, and prednisone. These drugs are used to treat asthma, rheumatoid arthritis, psoriasis, colitis, and a wide range of other conditions. Antiseizure drugs are linked to bone loss, as well.

Next Article:

Osteoporosis Glossary

  • Bone Mineral Density - A measurement of the amount of calcium and minerals in bone tissue.
  • Calcium - A mineral in (and vital to) your bones. If your body lacks calcium, it takes it from bones.
  • DEXA (dual energy X-ray absorptiometry) - a test used to measure bone mineral density.
  • Osteoporosis - A decrease in bone density, which increase the risk of fractures.
  • Vitamin D - A vitamin that helps your body absorb calcium.
  • View All Terms

How do you exercise for strong bones?