MLB tests players at the Major League and Minor League levels for steroids and other performance-enhancing drugs, as well as amphetamines. MLB prohibits the use of HGH, but does not test for it because blood testing has not been collectively bargained and is characterized by some as unreliable.
WADA president John Fahey said "enhanced use of intelligence and strategic out-of-competition testing" is key to HGH detection in the future, and that blood collection is a necessary part of that pursuit.
"International scientific experts agree that HGH is found in extremely small quantities in urine and that a potential detection method for this substance in urine is years away," Fahey said in the statement. "Joint blood and urine testing is the only way to go for sports organizations to ensure that they use proper means to protect the integrity of their sport."
Rob Manfred, the executive vice president for labor relations and human resources for MLB, responded to the organization's latest statement regarding baseball's approach to HGH, releasing a statement outlining MLB's ongoing efforts in the area of detecting the banned substance.
"Major League Baseball representatives have publicly stated numerous times, including at the Partnership for Clean Competition [PCC] conference hosted at our offices two weeks ago, that we are currently exploring the feasibility of conducting blood testing for HGH in the Minor Leagues as soon as practical," Manfred said. "WADA was not represented at the PCC conference and apparently is unaware of baseball's efforts in this regard.
"Blood testing in the Major Leagues is subject to collective bargaining. We have opened a dialogue on the issue of HGH testing with the Major League Baseball Players Association and look forward to working with them to achieve an appropriate resolution."
The MLBPA did not have an immediate response to the WADA statement.
The issue of HGH testing has been in the forefront since the United Kingdom Anti-Doping authority announced a two-year ban for rugby player Terry Newton last month. Newton became the first athlete suspended for using HGH after failing a blood test.
At the time of that revelation, the MLBPA released a statement saying it will continue to monitor HGH testing and will work closely with the Commissioner's Office to improve the current testing program.
"We look forward to continuing to jointly explore all questions associated with this testing -- its scientific validity, its effectiveness in deterring use, its availability and the significant complications associated with blood testing, among others," the statement read.
The WADA statement Thursday said that blood testing in MLB should be implemented as soon as possible.
"Blood sample collection has been conducted for years in many sports around the world without any problem. So why do others still refuse it?" the statement read.
John Schlegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.