Human growth hormone
Human growth hormone (aka HGH, somatotropin, somatotrophin, rHGH, rhGH) is a performance-enhancing drug banned by Major League Baseball. The exact effects, both positive and negative, of HGH use in normal adults are not known in detail because of a lack of reliable scientific studies. Nonetheless, there is a common belief that HGH use is likely to lead to muscle growth and reduced fat levels similar to those produced by steroid use.
Although HGH was banned by MLB at the same time as steroids and other performance-enhancing drugs, it could not be detected by existing tests: MLB used only urine tests, and the only existing test for HGH was a blood test whose effectiveness was questionable. Detecting HGH is difficult for two reasons: one is that HGH is a peptide hormone, which is a completely different class of chemical from most drugs and consequently impossible to find using conventional approaches to drug testing; the other is that HGH exists in the body naturally, so any test must be able to tell the difference between natural and unnatural levels. In early 2010, it was announced that a more reliable blood test had been developed, and MLB indicated its intention to begin testing minor league players for the substance. On August 18, 2011, Mike Jacobs became the first player in organized baseball to test positive for HGH. He received a 50-game suspension and was immediately released by the Colorado Rockies.
HGH had been a popular topic for speculation about performance enhancing drug use. Untestable drugs such as HGH left a large loophole in baseball's drug testing regime, giving fans a reason to wonder which players may have been using. These speculations received confirmation when the San Francisco Chronicle reported that Jason Giambi had admitted to HGH use to the Grand Jury in the BALCO case. Later, Jason Grimsley admitted to HGH use after an FBI raid on his house, and David Segui confirmed that he had also used it, albeit with a prescription and under medical supervision.
In the spring of 2012, Major League Baseball began submitting players to blood testing for HGH. However, the invasive nature of the test, which requires taking 6 to 8 vials of blood, and its potential ill effects on players resulted in a desire expressed by the Players' Association and many players that no such testing be conducted during the regular season. This was changed in 2013, when MLB and the MLBPA agreed on a modification to the Collective Bargaining Agreement that allowed in-season blood testing for HGH.