The former England midfielder was taken ill last week and the 42-year-old was taken to hospital to undergo tests.
A subsequent statement from the League One club, where he works as Under-23s coach, said he had been diagnosed with primary sclerosing cholangitis and now requires a transplant.
Dyer said: "Unfortunately, I was diagnosed with a condition of the liver a couple of years ago, that would lead to me one day needing a transplant.
"Over the next week, test results will confirm when I need to go through this procedure.
"I see myself as a very positive person that will overcome this minor setback. I'm very grateful to the club, the supporters and the general public for their messages of support over the past week.
"I would like to ask everyone now to respect my privacy, and my family's privacy."
Dyer, who won 33 senior England caps, started his career with Ipswich before going on to play for the likes of Newcastle and West Ham.
He recently took part in Channel 4's 'Celebrity SAS: Who Dares Wins' but had to withdraw due to injury - reportedly a punctured lung.
Dyer bravely opened up about the harrowing experience of being sexually abused by his great uncle as a child on the show, and shed insight on how he struggled to deal with the trauma as an adult in an emotional interview with talkSPORT in November 2020.