Medicine: Building Up Brittle Bones

Estrogen and fluoride vs. osteoporosis

“Granny fell and broke her hip.” When the word first passes around the family circle, younger members especially are not seriously concerned. But that cavalier attitude quickly changes in the tragic sequence of events that so often follows: circulatory problems, including blood clots, respiratory infections like pneumonia, severe muscle atrophy during prolonged immobilization. Each year about 200,000 older Americans suffer from this seemingly minor accident. As many as 40,000 die of complications within six months, and another 40,000 are so disabled that they require chronic care in nursing homes for the rest of their lives.

The majority of victims are elderly women, most of whom suffer from osteoporosis, a progressive thinning of the bones that can leave the skeleton too brittle to withstand even minimal stress. Indeed the bones of the spine can become so papery that they collapse; five vertebrae may fill the space normally occupied by three, causing a protuberance known as “dowager’s hump.” Says Eleanore Bennink, 73. of Southgate, Mich.: “I was 5 ft. 3 in. when it started. Now I’m 4 ft. 10 in. The pain was horrendous.” The condition is prevalent among older women because their frames are smaller than men’s and after menopause the ovaries cease to produce estrogen, the female hormone that plays an important role in the retention of bone. Normally the body forms new bone tissue as old bone is broken down in a process called resorption. Estrogen helps regulate the rate of this remodeling; if the hormone is deficient, bone is not replaced as quickly as it is removed. Smoking, poor diet and lack of exercise increase a woman’s chances of developing osteoporosis.

Until recently, treatment has generally been limited to prescribing supplemental estrogen, to slow the resorption rate, and calcium, to facilitate the formation of new bone.* Using a computerized axial tomography scanner, doctors at the University of California in San Francisco are able to take three-dimensional X rays of the bones, measure the loss of minerals and devise an estrogen dosage sufficient to maintain the resorption balance. Says Kaiser-Permanente Endocrinologist Dr. Bruce Ettinger, who does research at U.C.S.F.: “We’ve been trying to find the smallest dose of estrogen that will prevent osteoporosis. I think we have the answer.”

Keeping the dosage to a minimum is crucial because estrogen has been found to increase the incidence of uterine cancer. Doctors acknowledge the risk, but many say it is worth taking. Explains Endocrinologist Dr. Michael Kleerekoper of Detroit’s Henry Ford Hospital: “The cancer produced by estrogen is curable. Osteoporosis is not. It’s a trade-off.” Adds Dr. Gilbert S. Gordan, professor of medicine at U.C.S.F. “What we are talking about is saving women a lot of pain and deformity and fracture.”

Doctors at Henry Ford Hospital and the Mayo Clinic in Rochester, Minn., believe they may have found a treatment that is as effective as estrogen but without its troubling side effects. In a twelve-year study, Dr. B. Lawrence Riggs and a team of Mayo physicians treated women with large doses of sodium fluoride combined with calcium. Sodium fluoride stimulates bone-forming cells to produce new bone faster than the old bone is resorbed. The Mayo researchers will now study the mechanical quality of the new bone, trying to determine if it is as strong as the tissue produced normally. Preliminary results indicate that the sodium fluoride treatment does restore the resorption balance and, in some cases, the scales have been sufficiently tipped to fill out once depleted bones. In half the patients studied, women developed very low fracture rates after the first year of therapy. Says Dr. Riggs: “You have to be very careful about saying cure, but in five years, fluoride may be on the market as a treatment. We are very excited about it.”

*Experts estimate that at puberty, when there is a spurt in bone growth, people require 1,200 mg of calcium daily (the equivalent of four glasses of milk or about 6 oz. of hard cheese). Postmenopausal women require 1,500 mg to offset the resorption process.