By Barbara Bronson Gray
While the study raises important questions about the safety of human growth hormone treatments, the study's French researchers encouraged parents to discuss the pros and cons of treatment with their child's physician.
"For children and adolescents currently on growth hormone treatment, the treatment should not be stopped, but the doctor prescribing the treatment should be consulted," said study author Dr. Joel Coste, head of the biostatistics and epidemiology unit at Hotel Dieu at the University of Paris.
One expert agreed that the finding should give parents pause.
"The study represents a kind of yellow light that should make people stop and think about [the potential risks]," said Dr. Rebecca Ichord, director of the pediatric stroke program at the Children's Hospital of Philadelphia.
"People view technology in medicine as a way to fix things, but the bad news is that when we try to fix things sometimes there is a price," said Ichord, who wrote an editorial accompanying the study.
The research was published online Aug. 13 in the journal Neurology .
Artificial growth hormone is used to treat children and teens when their pituitary gland fails to produce enough natural growth hormone. It is also given to speed up growth and increase height when a child is short, either because of genetic abnormalities, chronic kidney disease, or below-normal signs of growth at birth. Increasingly, growth hormone is being used because parents believe their child might benefit from being taller, according to Coste.
While the U.S. Food and Drug Administration approved growth hormone in 1985, Coste noted there is still little known about the potential impact of the hormone on long-term health.
And a recent survey found that an increasing number of U.S. teens are using growth hormone simply to boost their muscles and athletic ability. The percentage of teens who admitted to using growth hormone more than doubled between 2012 and 2013, going from 5 percent to 11 percent, the Partnership for Drug-Free Kids Survey revealed.
The current research was done as follow-up to a 2012 French study that showed larger numbers of deaths from strokes in those taking growth hormone.
The researchers wanted to dig a little deeper this time. The first study tapped French data on long-term mortality and illness in a mandatory registry for patients treated with growth hormone. The new research analyzed incidence of all stroke subtypes among adults between 2008 and 2010 who were treated as children with growth hormone between 1985 and 1996.
The study included almost 7,000 children born before 1990 who started treatment between 1985 and 1996. From 2008 to 2010, the researchers followed up with health questionnaires and tapped information from medical records and death certificates, if a participant died.
Participants were, on average, 11 years old when they started growth hormone treatment and took it for about four years. Comparison data for stroke incidence in a comparable time period were obtained from population-based registries in France and the United Kingdom.
During the follow-up time period, 11 of the participants had a stroke; eight of the strokes were hemorrhagic. The strokes occurred at an average age of 24, and four people died as a result of the stroke.
That compared to three to seven expected strokes in total in the general populations, with two of those being hemorrhagic strokes.
Hemorrhagic stroke occurs when a weakened vessel ruptures and bleeds into the surrounding brain tissue, according to the American Heart Association.
Despite the large size and scope of the study, the researchers said there are notable unresolved questions. Scientists still do not fully understand why or how growth hormone may affect stroke risk, or what characteristics of a child or adolescent might increase his or her individual risk. And while the study showed an association between use of growth hormone and an increased stroke risk, it did not establish a cause-and-effect relationship.
Researchers still have no idea what the effect of taking growth hormone in childhood might have over longer periods of time.
"It's an additional elephant in the room, what happens to these individuals when they experience aging," said Ichord. "Who knows what the same population might be like in their 40s, 50s or 60s?"
Ichord said physicians treating children need to evaluate potential lifelong implications of treatment. "We in pediatrics need to be humble about things we do to children when they are young and be prepared to look at the long-term outcomes of treatments we prescribe," she noted.
Ichord encouraged people who are taking or have taken growth hormone therapy to be informed about how to help prevent strokes, how to identify early signs of a stroke and the importance of seeking treatment quickly.