In PWS, growth hormone is effective not only in increasing height, but also in:
In addition to these positive effects on growth and body composition, growth hormone therapy produces positive effects on development, behavior, and quality of life in those with PWS.
The use of the treatment is widespread in PWS. As reported in the Global PWS Registry, which has more than 2,000 registered participants diagnosed with PWS, 91% of respondents say their participant is using or has used growth hormone. Of those participants who have used growth hormone, 71% began before age 2, and 93% perceive they have received benefit from the drug.
Growth hormone therapy can be initiated at any age in individuals with PWS, but there is accumulating evidence that starting growth hormone therapy early provides the most benefit. According to expert Consensus Guidelines, there is strong evidence supporting the use of growth hormone for PWS beginning in infancy. Studies have shown the benefits of growth hormone treatment when started between 4 and 6 months – and as early as 3 months – of age. A study also has concluded that growth hormone therapy in people with PWS less than 2 years of age is safe and improved body composition, and that infants who received growth hormone before the age of 15 months started to walk earlier. There is currently not complete consensus on exactly when growth hormone should be started; a pediatric endocrinologist familiar with PWS should be consulted.
Proper nutritional management remains a mainstay during growth hormone therapy. Regular contact with a dietitian is important throughout the lifespan of the person with PWS.
Several studies support the benefits of growth hormone therapy for children with PWS; some are described below. In addition, a meta analysis has been published describing these benefits.
A study by Carrel et al found improved mobility and body composition in young children who had started growth hormone therapy as infants or toddlers. A follow-up study compared a group of 6-year-olds who received therapy to another group of children, matched for age, who had not received therapy. Looking at a battery of tests, including height, body fat, “good” and “bad” cholesterol, motor strength, and agility, kids taking growth hormone from a young age came out on top for all measures.
The authors concluded that growth hormone therapy, started in infants, significantly changes the natural history of PWS in a beneficial and clinically meaningful way.
Another study by de Lind van Wijngaarden and colleagues followed 55 children in the Netherlands over four years of growth hormone therapy. The children experienced height increases similar to their peers, and had improvements in body composition, decreases in body fat, and stabilization of lean body mass.
Other benefits noted in the medical literature include improved:
There is some evidence that growth hormone therapy may improve cognitive outcomes in children with PWS.
A study by Dykens and colleagues showed that children with PWS who received human growth hormone had higher IQ scores and better communication and daily living skills than children who had not received human growth hormone. This study is consistent with other studies that suggest that “earlier is better.” Children who started human growth hormone before 12 months of age had higher IQ scores compared to children who started at 1 to 5 years of age.
Endocrinologist Jennifer Miller, MD, describes the cognitive benefits of growth hormone therapy for people with PWS in this FPWR research conference presentation.
A study by Donze and colleagues reported in The Journal of Clinical Endocrinology Metabolism found that growth hormone treatment also results in improved mental and motor development in very young children. During three years of treatment, mental development in children increased 21.5% and motor development increased 36.3%. Researchers also concluded that the younger children are at the beginning of growth hormone treatment, the greater the improvement in psychosocial development.
Research on growth hormone therapy supports its benefits when used for PWS treatment, while continuing its reassuring safety profile. This means that for all the benefits the treatment delivers, it does not increase risks of other health issues.
One concern when growth hormone therapy first came into clinical use was whether its use in children might increase the risk of leukemia. However, a study by J. Bell followed almost 50,000 children who received growth hormone between 1985 and 2006. Some children had PWS, and some were undergoing growth hormone treatment for other reasons. They found that slightly less than the expected number of children in this group developed leukemia. For children who had cancer previously, there may be an elevated risk of cancer recurrence with growth hormone, which is consistent with previous reports and is not relevant for those with PWS.
Other concerns specific to PWS include scoliosis (curvature of the spine). Scoliosis is very common in PWS, and some physicians may be concerned about growth hormone use in individuals with PWS who develop scoliosis. But data suggests that human growth hormone does not worsen scoliosis outcomes. If anything, it is associated with slightly better outcomes, perhaps due to strengthened muscles. A study that compared children on growth hormone to those who did not receive growth hormone, and saw no difference in the rate or severity of scoliosis. Another study examined the incidence and severity of scoliosis in children with PWS who used GH for a longer period (8 years) compared to those who did not use GH. There was a similar incidence of scoliosis, but less curve (better outcome) in the children who were given GH (final publication is here). Thus, the general consensus of PWS experts is that scoliosis is not a reason to stop or change growth hormone therapy, although individual cases should be discussed with health care professionals who are knowledgeable about PWS.
The Foundation for Prader-Willi Research (federal tax id 31-1763110) is a nonprofit corporation with federal tax exempt status as a public charity under section 501(c)(3).
