Older women with osteoporosis could get lasting benefits from a few years on growth hormone, a new, small trial suggests.
Researchers found that when women with the bone-thinning disease took growth hormone for three years, their fracture risk was still reduced seven years later. Before entering the study, 56 percent of the women had suffered a bone break; over the 10-year study period, 28 percent sustained a fracture.
But the study, reported online Aug. 27 in the Journal of Clinical Endocrinology & Metabolism, only involved 55 women who used growth hormone.
And experts said it is unlikely to become an approved treatment for osteoporosis any time soon.
Still, the results are “pretty exciting,” since they show a sustained effect on women’s fracture risk, said Dr. Jerome Tolbert, an endocrinologist at Mount Sinai Beth Israel in New York City.
“Osteoporosis is a serious problem, and we need to do a better job of preventing and treating it,” said Tolbert, who was not involved in the study.
However, more research is needed before growth hormone could become a treatment option. “Do we need more studies to confirm the safety and effectiveness? Yes, we do,” Tolbert said.
In the United States, about 52 million people have low bone mass or full-blown osteoporosis, according to the National Osteoporosis Foundation. And among women older than 50, roughly half will suffer a fracture due to thinning bones.
There are a number of bone-protecting medications that can cut that fracture risk, including bisphosphonates such as Actonel, Boniva and Fosamax, plus generics; the injection drugs denosumab (Prolia) and teriparatide (Forteo); and raloxifene (Evista), a pill that has estrogen-like effects on bones.
A recent review found that, overall, the drugs reduce the risk of spine fractures by 40 percent to 60 percent. They also curb the risk of other bone breaks, including hip fractures, by 20 percent to 40 percent.
But while many options exist, Tolbert said he could foresee “a place for growth hormone to fit in.”
What’s “interesting,” he added, was that it only had to be taken for a finite amount of time in this trial, and not continuously. So that’s a potential advantage, he said.
Right now, growth hormone is approved to treat just a few medical conditions, including growth hormone deficiency in children and adults.
It is not approved to remedy the normal decline in growth hormone that comes with aging. However, some “longevity clinics” have been promoting growth hormone as a fountain of youth that can increase muscle, trim fat and improve stamina in aging adults, according to the U.S. Food and Drug Administration (FDA).
For women with osteoporosis, growth hormone does indeed stimulate bone formation, according to Dr. Emily Krantz, the lead researcher on the new study.
It may also enhance muscle mass and balance, which could help women avoid falls, said Krantz, of Sodra Alvsborgs Hospital in Boras, Sweden.
But there are also risks. According to the FDA, the side effects of growth hormone include fluid retention, joint and muscle pain, and elevated cholesterol and blood sugar. There are also concerns about a potential link to cancer risk.
In this trial, though, there were few side effects, according to Krantz. Some women had swelling in their hands and feet, but there were no lasting effects on blood sugar or cholesterol levels.
The findings are based on 80 women with osteoporosis who were randomly assigned to take daily injections of either growth hormone or a placebo for 18 months. After that, the hormone group continued on the treatment for another 18 months. All of the women took calcium and vitamin D.
Krantz’s team also compared the study group with a random sample of 223 women the same age who did not initially have osteoporosis. Over 10 years, the rate of bone fracture in that group rose from 8 percent to 32 percent.
In contrast, the study patients saw their fracture rate drop by half over time — from 56 percent to 28 percent.
That decline, Tolbert said, is “pretty remarkable.”
It’s not clear, though, how much of the credit goes to growth hormone. There was no significant difference in fracture rates between women who’d used the hormone and those who’d used a placebo. And part of the benefit, Krantz’s team said, could have come from awareness of fall prevention and other medications that some women took during the seven-year follow-up.
And in the “real world,” there are practical barriers to using growth hormone for osteoporosis — including its high cost.
“It’s unlikely,” Krantz acknowledged, “that it will be used [for osteoporosis] in the foreseeable future, because the treatment is so expensive and has to be overseen by a specialist clinic.”
Krantz said her team has no plans for a larger trial, but will keep following the patients who’ve already received growth hormone.
The National Osteoporosis Foundation has more on treating osteoporosis.