Osteoporosis

Osteoporosis literally means “porous bones”. Osteoporosis is when the holes within the honeycomb matrix of the inner bone become larger, making the bone fragile. The world Health Organization defines osteoporosis as bone density that is 2.5 standard deviations below an average 35 year old. 10 million Americans have osteoporosis and 1.5 million succumb to bone fractures each year. When bone density is between 1.0 and 2.5 standard deviations below an average 35 year old, one has osteopenia. Approximately 20-30 million Americans have osteopenia. Do not be alarmed if your bone density is slightly low because you are being compared to bone at its maximum density. Women reach maximum bone density at age 35. Older bone is constantly being replaced by newer bone tissue. After age 35, bone is broken down faster than it can be rebuilt. Bone loss is a consequence of advancing age, but it is much more rapid in women after menopause. The loss of estrogen and progesterone at menopause is responsible for the majority of the disease. Women lose the majority of their bone in the first five years after menopause if they are not taking supplemental estrogen and progesterone. This is why 80% of all people with osteoporosis are women. The most common area for an osteoporotic fracture is within the vertebral bodies in the spine. This can result in curvature of the spine, loss of height, chronic back pain, and leads to further fractures in the vertebra. The second most frequent place of a fracture is in the hip. Hip fractures are so serious that approximately 25% of women hospitalized secondary to a hip fracture will die within a year.

There are no symptoms of osteoporosis. Besides being a woman, there are many other risk factors for osteoporosis. Uncontrollable risks include an early menopause, having a family history of osteoporosis, having a small frame, and fair skin (Caucasian, Asian). Medical and nutritional risks include hyperthyroidism, calcium deficiency, alcohol, smoking, and corticosteroid use. The national Osteoporosis Foundation recommends that women over the age of 65 get a bone density test. I think it is important to get one at the age of 50 so a baseline is established prior to menopause. Any woman with a documented vertebral, hip, wrist, or rib fracture, should get a bone density test right away. The best test is called a dual x-ray absorptiometry (DEXA) scan. This test accurately measures the density of the bone at the three most common areas of fractures; the spine, hip and wrist.

Non-medical prevention and treatment of osteoporosis involves adequate calcium (1000-1500 mg daily), vitamin D (400-800 U daily), and weight bearing exercise. Vitamin D enables calcium to be absorbed by the bones. The most common source of vitamin D is from direct sunlight. Adequate magnesium intake is critical because magnesium helps the body absorb calcium. Even with adequate magnesium, the stomach can only absorb 500mg of calcium at a time, so calcium should be taken three times a day. There is nothing better than adequate estrogen and other hormones in the prevention of osteoporosis. Estrogen helps prevent osteoporosis by inhibiting bone resorption. Progesterone, on the other hand, stimulates bone formation. Testosterone also stimulates the formation of new bone and aids in the absorption of calcium. DHEA both inhibits bone resorption and stimulates bone formation. Raloxifene (Evista) is also used for osteoporosis but it has only been shown to prevent fractures in the spine. Alendronate (Fosamax) and risedronate (Actonel) are biphosphonates and have been shown to rebuild bone by preventing bone resorption. It has to be taken on an empty stomach because food inhibits its absorption. Calcitonin is another drug that inhibits bone resorption. It is not as effective as estrogen or the bisphosphonates. Calcitonin reduces the risk of spinal fractures but does not have much of an effect on the hip. It is available as an injection or a nasal spray. Teriparatide, recently approved by the FDA, stimulates the growth of new bone by increasing the number of osteoblasts (bone-forming cells). Taking folic acid may one day prove to be beneficial because folic acid decreases homocysteine levels. Two recent studies showed that people with high homocysteine levels were at much greater risk for hip fractures.