Each player was given a blood test for HGH during spring training as part of the labor contract that was agreed to in November, which allows blood testing during the offseason and spring training, and if there is reasonable cause.
Union head Michael Weiner, speaking to the Baseball Writers' Association of America before Tuesday night's All-Star game, said players will be discussing whether to expand testing to the regular season in 2013.
"We have just elected, as we do in June of even-number years, a new executive board, a new group of player reps, and over the second half of the season we'll be trying to generate what the consensus is," Weiner said. "There is at least a possibility, I'm not going to predict which way it's going to go, but there's at least a possibility that we could have in-season testing of some form as soon as next year."
The blood testing that began in spring training could be expanded to the postseason, but that doesn't appear likely to happen this year.
"Every single 40-man roster player was tested for blood this spring. I believe, I'm not certain, but believe that is the most athletes that have ever been tested for blood in any sport at any time, to have 1,200 tests," Weiner said. "What our agreement says is that the parties would get together to discuss the possibility of extending random testing into the postseason. Those discussions will happen at some point at the end of the year."
No major leaguer has been announced as testing positive for HGH. Under the new labor contract the identity of substances that cause positive tests are made public.
HGH is detectable only in blood tests, not in the urine tests that baseball has used since 2004.