"Izzy was not going to be here at the end of the season," Adkins told the Scunthorpe Telegraph.
"The January window approaches now, players will become available and Izzy has become available. It was not a hard decision"
Adkins also hinted that he may want to bring another central defender to the club in January.
"We look all the way through the team, if we want to get promoted we need to stop conceeding goals," he added
""We need to keep more clean sheets, so that is on the top of our list"
The United boss also reported that Kevan Hurst and Kenny Milne also trained but will not be in contention for a place in the squad until January.