Growth Hormone Therapy Safe and Helpful for PWS Adults, Study Finds

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by Vanda Pinto, PhD |

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Growth hormone treatment is safe and helps to increase lean body mass and reducing body fat in adults with Prader-Willi syndrome (PWS), according to an analysis of published studies.

Findings also suggest that such improvements in body composition might lower the risk of cardiovascular problems in adults with the disorder.

The study, “Growth hormone treatment for adults with Prader-Willi syndrome: a meta-analysis,” was published in The Journal of Clinical Endocrinology & Metabolism.

PWS is a complex developmental disorder associated with weak muscle tone (hypotonia), feeding difficulties, and poor growth. Children with PWS have an insatiable appetite, causing them to overeat and gain excessive weight.

Chronic overeating and obesity can put patients, especially as they reach adulthood, at risk for heart disease. Exercise is known to aid weight loss and cardiovascular health, but vigorous exercise is difficult for PWS patients due to their hypotonia and sometimes severe behavioral issues.

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Previous studies have shown that growth hormone (GH) treatment can improve physical health and cognition, as well as quality of life in children with PWS. These improvements were observed in PWS children with proven GH deficiency, as well as in those without it.

Use of growth hormone therapy has become standard for children with PWS, but concerns remain regarding its safety in adults.

An international team of researchers conducted an analysis of multiple studies — called a meta-analysis — to evaluate the efficacy and safety of GH treatment in adults with PWS. The analysis focused on improvements in body composition, body mass index (BMI), changes in low-density lipoprotein cholesterol levels, cardiovascular measures, cognition, life quality, and general safety.

Several databases were screened, and a total of 29 articles analyzed. Nine of these were findings of randomized clinical trials that included a control group (RCTs) for comparison, and 20 were non-randomized trials without controls (NRCTs). Studies of GH treatment that spanned less than six months were excluded from the analysis.

All RCT studies found that body composition improved, with a reduction in fat mass and an increase in lean body mass. A person’s lean body mass is the body weight minus body fat.

Similarly, the NRCTs showed that GH treatment for 12 months resulted in a significant increase in mean lean body mass —around 1.95 kg (about 4.3 pounds) — and a decrease in mean fat mass of 2.23%.

Studies also found that GH use in adults with PWS was safe, with no major safety concerns reported regardless of whether they were new of the therapy or had used it previously.

No significant changes in BMI or in low-density lipoprotein cholesterol levels, also known as the “bad cholesterol,” were observed with GH treatment.

Conclusive results were not evident regarding the effects of GH treatment on cognition and life quality. While some studies found improvements, others did not.

“Different instruments were used across the studies, which makes it hard to compare the results,” the researchers wrote. “Furthermore, most studies were small and short-term studies, which might result in less potential for improvements in cognition and QoL [quality of life].”

Results were also conflicting on possible improvements with treatment use on bone mineral density, with the two RCTs that evaluated this finding no significant differences between patients given GH and those on a placebo.

Likewise, no strong conclusions could be drawn regarding changes in the risk of heart disease among PWS adults given growth hormone therapy under the cardiovascular parameters used in the various studies. For instance, fewer thromboembolisms (blood clots in deep veins) were reported in one controlled study, but patients in the non-treatment control group were older and had less frequent multidisciplinary care, which the scientists noted could influence this finding.

“More research is needed and close monitoring of the cardiac function is indicated. Since reduction of cardiovascular risk due to improvements in body composition by GH [treatment] takes many years, long-term studies are needed to confirm the impact of GH on cardiovascular risk,” the researchers wrote.

GH treatment did not appear to lower glucose metabolism, with no increase seen in fasting glucose levels, of note because GH neutralizes the effects of insulin on glucose and lipid metabolism.

“The results of the present meta-analysis confirm that GH [treatment] improves body composition in adults with PWS, without safety concerns,” the researchers concluded.

“As poor body composition plays a key role in the high cardiovascular morbidity of adults with PWS, improving body composition might reduce cardiovascular complications in this vulnerable patient group,” they added.

Limitations to this work included the small number of studies evaluated, and the fact most of the studies did not distinguish between patients with known GH deficiency and those without.