The 23-year-old midfield ace suffered a blow to the face early in the second half at Upton Park.
And lightning struck twice moments later when his replacement, Jay Tabb, hobbled off with a hip problem.
But while Tabb is unlikely to be ready for tomorrow's clash, Karacan is winning the battle.
Jimmy Kebe is also available despite suffering cramp against West Ham.
Boss Brian McDermott, explained: "Jimmy had cramp and should be fine. We're not sure about Tabby but Jem should be okay.
"We need as many fit players as opssible for the run-in, we want everyone invovled."
In stark contract, Leeds boss Neil Warnock has described the club's latest suspensions as "total irresponsibility," as he prepares for tomorrow's fixture with three players missing.
Paul Connolly was sent off in the weekend defeat to Watford while Adam Clayton received his 10th booking of the season so both will be suspended.
Former Reading loan defender Darren O'Dea is also serving a two-match after being sent off against Millwall.
It means Warnock may be forced to draft in youngsters to bolster his squad, and Leeds' boss fumed: "The [Connolly] sending off summed up Saturday.
"We're going to go to Reading with no Connolly, no Clayton, and no O'Dea. Total irresponsibility really. So why worry? We'll give some of the kids of a chance now."
"But I don't think Reading is one for the kids if I'm honest. I think we've got to hang in there as best we can and give them a tough game."
Leeds winger Aidy White is also a doubt through injury while teenage defenders Zac Thompson and Charlie Taylor could be in contention for a place in the squad.