Teens' Weight Loss Surgery May Weaken Bones03/28/11
MONDAY, March 28 (HealthDay News) -- Teens who undergo gastric
bypass weight loss surgery can expect to have a decline in bone
mass, just as adults do, according to a new study.
Two years after the surgery, the bone mineral content of the 61
obese teens studied had declined, on average, by 7.4 percent, said
Dr. Anne-Marie Kaulfers, an assistant professor of pediatrics at
the University of South Alabama.
"At the moment, I do not think there is cause for alarm," Kaulfers said of the study findings. That's because the teens, who averaged 17 years old, still had bone mass within the normal range, she said. They had started with above-average bone mass for their age and gender.
The findings are reported online March 28 in the journal
Kaulfers and her colleagues decided to study the teens because a
loss of bone mineral content during adolescence, when they should
be approaching peak bone mass, could potentially compromise future
Studies of adults have also found that their bone mass declines
after the surgery.
Kaulfers did the study while at Children's Hospital Medical
Center in Cincinnati. Some of the participants were part of the
Teen-Longitudinal Assessment of Bariatric Surgery Consortium
supported by the U.S. National Institutes of Health.
All of the teens, 10 boys and 51 girls, had gastric bypass, a
procedure in which the stomach is reduced from the size of a
football to that of a golf ball.
The researchers measured bone mineral content and density by
dual-energy radiograph absorptiometry (DXA). When possible,
measurements were taken before surgery and then every three to six
months after the surgery for up to two years.
Called a "
z score," the teens' average bone mineral density scores
decreased from 1.5 to 0.1. A
z score of 0 is normal, Kaulfers said, and a negative score
would reflect low bone density.
Though what happens beyond two years is unknown, Kaulfers said
that the bone loss appears to be offset by the benefits of the
surgery, such as reducing the likelihood that the teens would
But teens who have the surgery need to be closely monitored, she
The bone loss after weight loss surgery may be due to the weight
loss itself, she said, or it could stem from other factors, such as
"I think the note of caution [about long-term follow-up] is very good," said Dr. Robin Blackstone, president-elect of the American Society for Metabolic and Bariatric Surgery and a bariatric surgeon in Scottsdale, Ariz.
She said she orders annual bone scans for her teen patients.
Dr. Neil Roth, an orthopaedic surgeon at Lenox Hill Hospital in
New York City, cited limitations to the research, which the study
"A fairly high percent didn't have a DXA scan before the study because they couldn't fit into the scanner" so there was no information on their bone status before the surgery, he said. That was the case for 64 percent, according to the study.
The long-term effect on bone health is unfolding for teens, so
until more research is in, he said, proceeding with caution would
"Make sure, as with any procedure, you exhaust your conservative measures first before you embark on something that is life-altering."
The U.S. National Library of Medicine has more on
gastric bypass surgery.
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