Etuhu's loan spell from Manchester City has been cut short by ankle ligament damage, with the forward returning to Eastlands for treatment.
However, in more positive news, McCormack is pushing to return in time for Saturday's home clash against QPR having not featured since the second weekend of the season due to a hamstring injury.
If he does not make the Rangers clash, then next Wednesday's Carling Cup trip to Aston Villa looks likely, but there is no chance of him featuring against Reading.
Full-back Kevin McNaughton remains the only other absentee, with the 27-year-old a couple of weeks away as he nurses an ankle injury.
Kick-off at the Madejski Stadium is at 8pm.