May 11, 2001

Asubstance secreted by four tiny glands in the neck could provide the most powerful treatment to date for osteoporosis, the bone-eroding disease that currently affects millions of Americans. In the May 10 issue of the New England Journal of Medicine, an MGH researcher working with scientists elsewhere reports that postmenopausal women with osteoporosis who took daily doses of human parathyroid hormone had significantly fewer spine and nonspine fractures. By promoting bone formation, the hormone also significantly increased bone density in their spines, hips and total bodies.

"The key to parathyroid hormone's fracture-thwarting powers is that it stimulates bone formation dramatically — it doubles the normal rate," says Robert Neer, MD, (left) director of the Osteoporosis Center at the MGH. Neer was the principal investigator in the international clinical trial sponsored by Eli Lilly and Company.

Currently available osteoporosis treatments slow bone resorption and bone loss. In contrast to these anti-resorption drugs, parathyroid hormone promotes bone formation. The study showed that after 21 months, the women taking parathyroid hormone had up to 13 percent more bone in their spine than those taking placebos. The average increase in bone for women taking currently available drugs is 9 percent or less, after two to three years of treatment.

The effect can be illustrated by a half-filled glass of water with a hole in the bottom. Current drugs concentrate on slowing the leak, but parathyroid hormone acts by replenishing the water at a greater rate than is lost through the leak.

In the study, 1,637 postmenopausal women with osteoporosis were placed on one of three regimens: placebo, 20 or 40 micrograms of parathyroid hormone injected each day.

"Parathyroid hormone reduces the percentage of women with osteoporosis who develop a new vertebral fracture by 65 and 69 percent. No other drug has reduced it more than 40 to 50 percent," says Neer. The hormone lowered a woman's risk of developing multiple spinal fractures even more strikingly — by 77 and 86 percent — and it also reduced the risk of nonspine fractures by 35 and 40 percent.

For more information about osteoporosis and this study, visit http://www.mgh.harvard.edu.