Osteoporosis: most answers yet to come.

Osteoporosis: Most answers yet to come

About 15 to 20 million people in theUnited States have osteoporosis, a loss on bone mass that can cause bones to shatter. But despite its prevalence, especially among postmenopausal women, a clear consensus on the causes, treatment and prevention of the bone disease has so far eluded the scientific community.

Some of the top osteoporosis researchersmet last week at the National Institutes of Health to consider the current state of affairs. After hearing two days' worth of sometimes conflicting data, the discussion leaders concluded the following:

Adequate calcium intake throughoutlife can slow or prevent age-related bone loss. However, the accelerated bone loss that occurs in women during the first decade or so after menopause cannot generally be reversed with calcium supplements alone.

Postmenopausal women can reducetheir bone loss with estrogen pills; calcium supplements used with estrogen can reduce the total amount of estrogen needed.

The best detection methods--CATscans and measurements of radiation absorption by bones--work well if performed carefully, but screening asymptomatic women is not cost-effective.

There is strong evidence, primarilyfrom studies of women, showing that being obese, being black and taking estrogen protect against osteoporosis, while advancing age, steroid use, lack of exercise and premenopausal removal of ovaries predispose individuals to it. The evidence implicating alcohol, cigarette smoking and low calcium intake in the development of the disease and heavy exercise in its prevention is moderately strong.

While not a consensus conference--aformal gathering organized by NIH to make decisions on controversial medical issues--the meeting last week reflected the most current medical reseach on osteoporosis. It echoed in part the findings of a 1984 consensus conference (SN: 4/14/84, p.238), though this time the researchers put more emphasis on estrogen as a preventive and less emphasis on calcium as a panacea.

Many questions, the conference participantsrepeatedly observed, remain unanswered. Conferees agreed that while most adults should and can eat a diet that gives them 1,000 milligrams of calcium a day (200 mg more than the National Academy of Sciences' recommendation), some people will benefit from additional calcium. "The problem is to determine who will and who won't,' says conference co-chair William A. Peck of Washington University in St. Louis. Some studies have even shown that extra calcium can't reduce post-menopausal bone loss. The data on exercise are also contradictory. And there is currently no treatment for established osteoporosis, though Peck suggests one may emerge from basic research into bone growth factors.