"Ask Dr. Cook" is a series of questions and answers regarding endometriosis. The current subject and answer can be found on Current Ask Dr. Cook web page. The questions may represent a summary of questions I have been asked by several different patients. I hope you find this information helpful. If you have a question you would like answered, please Submit A Question.

Bone Mineral Density Testing and Osteoporosis

While my primary interest is helping women with endometriosis and pelvic pain, I am also a certified densitometrist. A densitometrist is a physician who is a specialist in bone density evaluation and osteoporosis. Osteoporosis is a condition where the bone density, and thus bone strength, is much lower than the average adult. Technically, this definition applies to postmenopausal women (natural or surgical) and men over the age of 50. It is a huge health care problem that neither physicians nor patients fully appreciate. More women will die from osteoporosis and its associated complications than breast and uterine cancer combined. Over 13 billion health care dollars will be spent on osteoporosis in the U.S. this year. Fifteen to 50% of people experiencing an osteoporosis related hip fracture will die with in the first year and fully half of the survivors will loose their ability to live independently, most will end up in a nursing home. I have spouted out these numbers to many patients, but how this weekend has given me a reality on these numbers. I hope that many of you can avoid learning the reality of this disease the hard way.

It is possible to detect bone loss in the early stages and it is now possible to actually reverse bone loss and increase bone density and strength. A bone mineral density test determines the density and thus the strength of your bones.

A person's bone density reaches a peak during their early thirties. This is known as the peak adult bone mass (PABM). The PABM a specific individual achieves, depends upon many factors including genetics and the amount of calcium intake as a teenager and during the 20's. In women, the peak adult bone mass remains fairly stable until the perimenopausal years. As a woman's estrogen production starts to decrease, the bone density usually decreases.

The overall size of the bone does not change but as bone is lost (the density decreases), the individual bone fibers decrease in size and number and the air pockets within the bone increase in size and amount. Osteoporosis is defined as bone density which is -2.5 standard deviations below the average peak adult bone mass (PABM). Osteoporosis is usually a silent disease. Most patients with osteoporosis have no symptoms and are unaware that they have osteoporosis. A person's bones can thin out over the years and as this happens she or he is more and more likely to have a fracture (broken bone). We have all seen an old women with a hunched over back. She does not have poor posture, rather a broken spine. The vertebral bodies of the spine literally pancake (compression fractures) under their own weight. Hip fractures are even more serious in that in the first year following a hip fracture half either die or loose their ability to live independently.

We have the ability to diagnose low bone mass prior to a fracture and we have the ability to increase a patient's bone density through various medications. A low bone mass is the single most predictive factor of an individual's future risk of fracture. The most accurate method of determining an individual's bone mineral density is dual-energy x-ray absorptiometry (DEXA). It is a more accurate screening tool than cholesterol is for the risk of a heart attack or high blood pressure for the risk of a stroke. Bone loss within individual patients may vary at different skeletal sites. It is important to evaluate several different sites (e.g. spine, hip and or forearm) to adequately determine the individuals bone mineral density and thus their risk of fracture.

We compare the results of the bone mineral density test to the average PABM (not your PABM). This comparison is known as the T-score or young adult Z-score. The T-score represents the standard deviation (S.D.) above or below the average peak bone mass. A premenopausal woman can have a PABM which is below the average PABM. While this is cause for concern, a premenopausal woman with a low PABM is not considered to have osteopenia or osteoporosis. A postmenopausal patient has a "low bone mass" (osteopenia) and is at an increased risk of fracture if the T score is -1.0 SD to -2.5 SD Osteoporosis is defined as a T score 2.5 SD or more below the average peak bone mass. A person with osteoporosis is at a high risk of experiencing a fracture (broken bone). We are fortunate to live in a time when we have a test that can find the early stages of this disease and medicines that can actually build backup the bone density and thus reduce the risk of a bone fracture. Osteoporosis is a preventable disease.

Updatede October 29, 2005