(HealthDay News) — The percentage of teens who admit to using synthetic human growth hormone jumped to 11% in 2013 — more than double the 5% figure in 2012, according to a new survey from the Partnership for Drug-Free Kids.

In order to track the use of human growth hormone (hGH) and other performance-enhancing substances, the researchers surveyed more than 3,700 high school students. They also questioned 750 parents during in-home interviews.

Although gender did not significantly affect use of synthetic hGH, the researchers found race and ethnicity did play a role. The researchers found that 15%of black teens and 13% of Hispanics said they used the substance at least once, compared with 9% of white teens. 

There was also a strong link between use of hGH and steroids. Steroid use among teens also rose, from 5% in 2009 to 7% in 2013.

Using synthetic hGH and other performance-enhancing substances and products poses serious health risks, the study authors warned. There is a largely unregulated marketplace, they noted, involving a variety of products promising to boost muscle mass, athletic performance and physical appearance.