Nov. 6, 2008 -- Treating abnormally short children with growth hormone can increase their adult height, even in if they are not found to be growth-hormone deficient, according to a team of Swedish researchers who followed children for 20 years.
In a group of 151 children, the average height gain in those given the higher of two growth hormone doses was about 3 inches.
Doctors have known for years that giving growth hormone, which is naturally secreted by the pituitary gland, helps children who are known to be deficient in the hormone. But whether giving the hormone to children of short stature whose growth hormone levels are not deficient proves effective has not been known.
The children studied by the Swedish team had short stature due to other causes, such as idiopathic short stature (ISS), a condition in which laboratory tests, including a test to check levels of growth hormone, are normal and doctors can't pinpoint easily a specific cause for the lack of height. Others were small for gestational age, or born small. The shortest 3% of children fall outside the bounds of what is generally viewed as "normal" growth.
Boosting Height
Kerstin Albertsson-Wikland, MD, PHD, professor of pediatrics at the University of Gothenburg, was the study's lead author. Her team assigned the 151 children to no treatment or two different doses of growth hormone, given for an average of nearly six years. Children entered the study between 1988 and 1999 and were followed over a period of up to 20 years, until they reached their final height.
Children with parents of normal heights responded best, the researchers found. The higher dose produced better results than the lower dose.
The lower dose was 33 micrograms per kilogram of body weight a day; the higher dose was nearly double that.
While a third of those given the high dose and a fifth of those getting the low dose reached a final height well within normal ranges, none of those in the no-treatment group did.
The final height of boys in the no-treatment group averaged 5 feet 5 inches, while those in the higher-dose group reached a height of 5 feet 7 inches. The girls in the no-treatment group got to an average height of 4 feet 11 inches, while those in the higher-dose group reached nearly 5 feet 2 inches.
The study was supported by grants from a variety of sources, including Pharmacia/Pfizer, which provided the growth hormone but had no input in the study. The Swedish Research Council, the Swedish Foundation for Pediatric GH Research, and the Foundation Vaxthuset for Children also supported the research.
Growth Hormone and Height: Second Opinion
The study is called an important one by Wayne Moore, MD, section chief of pediatric endocrinology at Children's Mercy Hospitals and Clinics and professor of pediatrics at the University of Missouri, Kansas City.
Though there has been little argument in the medical community about treating children known to be deficient in growth hormone, there have been questions about whether those not deficient would gain any benefit from the treatment, he says.
The new study, he says, "proves to me conclusively that GH [growth hormone] therapy is of significant benefit in children who have non-GH deficient short stature, defined by current criteria," Moore tells WebMD.
That includes those with ISS and those born small for gestational age.
The goal of growth hormone therapy, Moore says, is to get children to their "genetic potential" in height, which is determined on an individual basis by taking into account the mother's and father's heights, and other factors.
"The effects are relatively modest," says David Allen, MD, head of pediatric endocrinology at the University of Wisconsin, Madison. But, he adds, "For some, 2 inches can be important." It might mean the difference, he says, between being able to drive easily, for instance, or not.
As promising as the results are, Albertsson-Wikland says the treatment is not universally recommended for all children with non-GH deficient short stature. It should only be recommended, Albertsson-Wikland says, for those predicted to have a good growth response, and only after careful discussion with the children and parents to decide if the children suffer substantially from the lack of height.
In ongoing research, the Swedish team has developed prediction models to help doctors decide which children will respond to treatment. They expect that report to be published soon.