While most cases of osteoporosis are caused by normal aging, hyperparathyroidism — when the parathyroid glands release an excessive amount of a hormone that regulates the body’s calcium levels — is another leading cause of the bone-loss disease.
Doctors commonly treat hyperparathyroidism using a class of prescription drugs called bisphosphonates, including alendronate and ibandronate, which are supposed to strengthen bones. A study led by scientists at UCLA, however, found that those drugs actually increase the risk of fracture. The research also revealed that patients who have surgery to remove the overactive parathyroid glands have fewer subsequent bone fractures.
About 400,000 people in the U.S. — 1-in-400 women and 1-in-1,200 men — have hyperparathyroidism, making osteoporotic fractures a major public-health and economic burden, says Michael Yeh, MD, associate professor of surgery and medicine and chief of endocrine surgery. “Hip fractures, in particular, are associated with significant rates of mortality, disability and loss of independence,” Dr. Yeh says. “Before this study, there were no data that compared parathyroid surgery with prescribing medication on the risk for fractures in people with hyperparathyroidism.”
The researchers analyzed data from more than 6,000 people who had been diagnosed with hyperparathyroidism between 1995 and 2010. All had healthcare coverage through Kaiser Permanente Southern California, and their demographic and socioeconomic profiles mirrored those of the greater Los Angeles population. Dr. Yeh describes the findings as “startling.”
Among the participants who were not treated for hyperparathyroidism, the study found there were 56 hip fractures per 1,000 people after 10 years. Among those who had parathyroid surgery, there were just 20 fractures per 1,000 people. And for those taking bisphosphonate medications, the study showed that the rate of hip fractures was 86 per 1,000 patients — higher than the combined rate for those who underwent surgery or did nothing at all.
The researchers also reviewed the number of bone fractures of all types (including hip fractures), and the results were similar. For people who did not receive treatment, there were 206 fractures per 1,000; for those who had surgery, 157 fractures per 1,000; and for those taking bisphosphonate medications, 303 fractures per 1,000.
Researchers also found that the risk for fractures among people taking bisphosphonates was higher whether people had osteopenia, or early bone loss, or full-blown osteoporosis, which Yeh said could suggest that either the drugs are harmful or the people taking them had other risk factors.
“Regardless, we were unable to demonstrate any benefit associated with this class of drugs, which have been around and routinely prescribed for more than 20 years,” Dr. Yeh says. “These findings should make bisphosphonates less attractive as an alternative to parathyroid surgery in patients with primary hyperparathyroidism.”