How did you get interested in endocrinology and metabolic bone diseases?

As a medical student, I was fascinated by how hormones deliver their messages to the cell, how they circulate in the blood, and make tissues respond. I’ve been interested in metabolic bone diseases since I started my training in 1971 at the National Institutes of Health (NIH) in endocrinology. I worked with Gerald Aurbach, one of the pioneering investigators in the field. My interest became a passion.

Osteoporosis is generally considered a women's disease. Do men get it too?

While we are interested in women and what can be done to prevent bone loss and to treat those who have already suffered bone loss, remember that 20 percent of the osteoporotic population is male.

We tend to assume that what we learn about women will apply to men, but this is not necessarily the case. Is lifelong low-calcium intake bad for men, as it is for women? A woman whose mother or grandmother had osteoporosis is at greater risk. We assume the same familial disposition for a man, but we don't know.

By asking what the differences are between the genders, we hope to glean information that will apply to prevention and treatment in men. To do this we need a very large national survey of men. Some data have become available from the Framingham study, and we are beginning to piggyback our long-term questions onto the database they already have generated.

What have you discovered?

One interesting piece of information is that some men who have sustained an unlikely fracture in childhood are at greater risk of developing osteoporosis later in life. This is a boy, for example, who falls on the ice or out of a tree and breaks his arm, an accident that would not necessarily lead to a break for most boys.

Why are people with osteoporosis at risk for fractures?

The big reason is, of course, that their bones are thinner and more fragile. In the elderly, an accident-prone house can add to that risk. General clutter, a scatter rug, or an electric cord left where someone can trip over it can predispose an osteoporotic individual to fall. Also, the elderly have slower reflexes and may not be able to catch themselves when they lose their balance. When older women do fall, they are more likely to fall to one side or the other, rather than forward or backward. A sideways fall is more likely to cause a broken hip, which in turn can lead to possibly fatal complications, such as pneumonia.

When should people be tested for osteoporosis?

Generally, we say the time to do the test is during menopause or perimenopause. But someone who has risk factors for osteoporosis—a mother with osteoporosis, a personal history of amenorrhea (having their period stop for an extended period of time), smoking, or a lack of dietary calcium and exercise—should probably get the test earlier. In this country, we are moving toward the notion of selective screening—meaning testing only those at risk not everyone. Fortunately, more and more people are coming in to get their bones measured before they have a problem.

"In the world of research, nothing ever ends. You may think your project has a five-year life span, but in the middle you may well uncover more questions. This is the essence of a productive research program. It never seems to end!" John P. Bilezikian, M.D.

So, who is at risk and who has been tested?

The figures are pretty sobering—out of the 20 to 25 million Americans at risk for osteoporosis, only three or four million have been tested. This means 80 percent of those who should be tested haven't been, due to lack of awareness or money. The bone density test, used for both men and women, is noninvasive, safe and painless.

If anyone wants more information, several organizations, such as the National Osteoporosis Foundation (800-223-9994), are active in letting people know about osteoporosis and other bone diseases.

What osteoporosis studies are you involved in?

Right now we have a group of 30 or 35 men in their early 50s with osteoporosis and no obvious reason for it: They have no history of taking steroids; they are not alcoholics; they have normal male hormone levels; don't smoke excessively; are active; and they have a history of sufficient calcium intake. Three-quarters come to our attention because of a fracture or back pain (unlike many women, who come to our attention because of the results of a bone density screening test).

We also have a group of 50 premenopausal women who have unexplained osteoporosis. We will study them also, since in women, it's assumed osteoporosis occurs due to lack of estrogen or to age. In these individuals, clearly their osteoporosis is not due to estrogen loss or to age. We have many other studies ongoing that focus on new therapies for osteoporosis.

What related areas have gender-specific issues?

Osteoporosis after organ transplants, for one. Dr. Elizabeth Shane in our group discovered that after a heart transplant men lost bone at a rate of 1 to 1-1/2 percent per month (compared to menopausal women losing that amount per year). It seems to be due to steroids and other immunosuppressive therapy that are administered.

Primary hyperparathyroidism is a disorder of calcium metabolism that can lead to kidney stones and bone loss. We don't know why women develop primary hyperparathyroidism three to four times more frequently than men. Is estrogen the culprit? Estrogen, in fact, has an interesting relation to the hormone that causes the disease. And of course men don't have a substantial change in estrogen levels as they age.

About John P. Bilezikian, M.D.

Dr. Bilezikian, professor of Medicine and Pharmacology at the College of Physicians and Surgeons, Columbia University, is Chief of the Division of Endocrinology and Director of the Metabolic Bone Diseases Program at Columbia-Presbyterian Medical Center in New York City. He has served at the NIH in the Mineral Metabolism Branch and as chair of the NIH Consensus Development Panel on Optimal Calcium Intake. He belongs to a number of professional societies and is former president of the American Society for Bone and Mineral Research. He was editor-in-chief of The Parathyroids (1994) and co-editor of Principles of Bone Biology (1996). Dr. Bilezikian's major research interests are related to the clinical investigation of metabolic bone disease, particularly osteoporosis and primary hyperparathyroidism.