Having an enlarged liver isn't enough to disqualify you by itself. But it may be an indicator of something much more serious.
Most of what would cause an enlarged liver should show up in your blood tests. So you may not learn the cause right away.
In the meantime, you should visit your regular doctor to find out the problem. There are several things that can stress the liver like that. I'm not going to list them here - better to get it from your doctor.
