The NBA and its players union are nearing an agreement that will allow testing of players' blood for human growth hormone (HGH), ESPN reports. If the league and the National Basketball Players Association can come to terms, testing could begin as soon as the 2013-14 season.

HGH is on the list of substances banned by the NBA, but the league has never been able to administer tests for it. Blood must be drawn to test for HGH, and the NBPA has never allowed its members' blood to be collected out of concern for the reliability of the testing.

The Major League Baseball Players Association and MLB agreed to test for HGH earlier this year. The agreement helped paved the way for other leagues to follow.

The collective bargaining agreement made by the NBA and its players' union after the 2011 lockout provided for a committee to establish the proper methods of HGH testing. Any possible testing agreement is a result of their efforts.