CHICAGO -- Premenopausal women who are obese may not be spared from osteopenia, as some research has suggested, but growth hormone therapy may help spur bone formation, researchers said here.
In a randomized, controlled trial in women with abdominal adiposity, those who took growth hormone for six months had significantly increased markers of bone growth, Miriam Bredella, MD, of Massachusetts General Hospital in Boston, and colleagues reported at the Radiological Society of North America meeting.
"This could be a potential therapy for postmenopausal osteoporosis," Bredella said during a press briefing, "but it's not a magic bullet," given that it's expensive and requires daily injections.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Explain that women who are obese but otherwise healthy may not be spared from osteopenia, and growth hormone therapy may help spur their bone formation.
- Note that heavy women on growth hormone also lost more abdominal fat, and that women who had the greatest decline in abdominal fat also had the greatest increase in bone formation, as did those with the best improvements in vitamin D levels.
Research has suggested that obesity may be protective against osteopenia and osteoporosis, but Bredella said studies by her group and others have shown that heavier women are not necessarily spared from diminished bone growth. Abdominal adiposity has been linked to low bone mineral density (BMD) and low growth hormone, they stated.
To investigate whether growth hormone can improve bone health in obese patients, Bredella's group enrolled 79 obese young women, mean age 36, with a mean body mass index (BMI) of 35 kg/m2.
Using MR spectroscopy to assess bone marrow fat, bone densitometry (DEXA) scans to assess BMD, and CT scans for abdominal fat and thigh muscles, the researchers found that nearly a third of patients in the study (32%) had osteopenia and 0.4% had osteoporosis.
For six months, patients took daily injections of growth hormone or placebo.
Across the study cohort, growth hormone significantly improved a biomarker of bone formation, P1NP, compared with those on placebo (P<0.05).
It also increased levels of bone marrow fat, which Bredella said she and colleagues speculated is "due to energy demand from increased bone formation," as well as levels of vitamin D, another marker of bone health.
The women on growth hormone also lost more abdominal fat; both subcutaneous and visceral fat melted away, although greater improvements were seen for lost visceral fat, Bredella said.
"Deep visceral fat decreased markedly following six months of growth hormone administration," she said during the briefing.
She added that treatment with growth hormone also increased muscle mass, but because "muscle is heavier than fat, patients' overall weight didn't change."
The researchers also found that women who had the greatest decline in abdominal fat also had the greatest increase in bone formation, as did those with the best improvements in vitamin D levels.
Bredella said that the results suggest a potential new treatment for bone loss and obesity, but that the findings are still preliminary.
For instance, in order to see an impact on fracture risk, she said, patients would have to be followed far longer than six months. There were no fractures in the study.
Although it's not a panacea for bone formation in obesity or for weight loss in general, she said, growth hormone may benefit some patients who have been unable to lose weight on other therapies, and potentially help diminish their risk of diabetes and cardiovascular disease.
A hormone-based weight loss program using human chorionic gonadotropin (hCG) has experienced a recent increase in popularity, but has also proven controversial.
Gary Whitman, MD, of MD Anderson Cancer Center in Houston, who wasn't involved in the study, said he "wouldn't expect to see it used very often for weight loss or for weight redistribution because it is very expensive and requires daily injections."
However, he agreed with Bredella, that growth hormone therapy "might be used in selected patients to begin a weight loss program."
Disclosures
The study was supported by grants from the NIH.
Study medication and placebo were provided by Genentech.
Primary Source
Radiological Society of North America
Source Reference: Bredella MA, et al "Growth hormone administration increases bone formation and bone marrow fat in premenopausal women with abdominal obesity" RSNA 2011; Abstract SSG09-01.