Children who receive growth hormone to treat short stature or hormone deficiency may be at an increased risk of strokes caused by burst blood vessels as young adults, suggests a new European study.
While the overall risk of stroke is still low, the researchers say people who received growth hormone should know about the link between the treatment and later stroke risk.
“This information should also be made available to those who misuse (growth hormone) for improving athletic performances, body building, and other questionable reasons,” the French and British researchers wrote in the journal Neurology on Wednesday.
Growth hormone, first approved in the U.S. in the mid-1980s, is given to children for a variety of reasons, including to treat pituitary gland problems and to increase the height of children with short stature.
The researchers, led by Dr. Amélie Poidvin of Paris Descartes University, write that little is known about the long-term effects of treating children with growth hormone.
An early report from an ongoing study suggested an increased risk of death from heart and vascular disease, the authors point out. In addition, people who naturally produce too much growth hormone are known to be at increased risk of aneurysms, which raises the likelihood of brain bleeds, known as hemorrhagic strokes.
In general, so-called ischemic strokes caused by a blood vessel blockage are far more common than hemorrhagic strokes, which are usually the result of a broken blood vessel. Strokes of any kind are rare in young people, so the researchers looked at how common they were among kids who took growth hormone.
For the new study, they analyzed data on 6,874 children who were born before 1990 and received synthetic growth hormone in France between 1985 and 1996. The children included in the study were treated for low-risk conditions, such as not producing enough growth hormone on their own or having short stature.
The researchers then followed up with those children an average of 17 years later – between 2008 and 2010. The young adults completed health questionnaires and the researchers also checked medical and death records.
They found that 11 of the young people who received growth hormone as children (or about two tenths of one percent) had strokes between the time of their treatment and follow-up. Of those strokes, eight were hemorrhagic strokes.
The study team then compared those numbers to stroke rates among people living in two cities, one in France and one in the UK.
They found the risk of stroke was up to 7.5 times higher among those treated with growth hormone, compared to people living in the two cities. The difference was largely due to hemorrhagic strokes.
While 73 percent of the strokes that occurred in the growth hormone group were hemorrhagic, less than a third of the strokes among those living in the two cities were of that type.
It’s not known how growth hormone may increase the risk of stroke, the researchers write, but it’s possible that the drug leads to changes in arteries and how they work.
“What the study shows is that the treatment was associated with the increase in the risk, as opposed to not having the treatment,” Dr. Rebecca Ichord said.
Ichord, who wrote an editorial accompanying the new study, is director of the Pediatric Stroke Program at the Children's Hospital of Philadelphia.
The researchers caution that their findings are limited by the small number of strokes and the fact that people included in the study may have other conditions related to both short stature and stroke.
Ichord said it’s important to know that this study does not prove that growth hormone causes hemorrhagic strokes, “but we know there may be some kind of association. There’s not really any preventive treatment for this type of brain bleed.”
Instead, she said, what people can do is educate themselves about the signs and symptoms of a stroke, which include confusion, severe headache, blurry vision and weakness in the face, arms or legs.
Dr. Laurie Cohen, director of the Neuroendocrinology Program at Boston Children's Hospital, said the discussion of whether to start or continue growth hormone treatment should be individualized.
“What really needs to be remembered is that there was a small number events and that this was an association,” said Cohen, who was not involved in the new study. “It doesn’t show that growth hormone causes strokes.”
Moreover, she said, there are studies showing no increased risk of death associated with growth hormone and there are risks to not treating children with growth hormone deficiency.
“Like anything else, further studies are needed,” she said.