An NFL spokesman said Friday that players have tested positive for HGH under the league's policy against performance-enhancing drugs.
According to Mike Florio of Pro Football Talk, NFL spokesman Joe Lockhart indicated that more than one player has tested positive for HGH since testing was introduced for it in 2014.
HGH testing is different from that of other PEDs in that it can only be detected from blood samples.
It isn't publicly known which players or exactly how many have tested positive for HGH over the past three years.
Although the NFL does announce when a player has been suspended for violating the substance-abuse policy, it does not reveal what the player tested positive for.