Dyer, 42, is in charge of the Under-23s at Ipswich Town and was in hospital this week to undergo a series of tests.
"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... I see myself as a very positive person that will overcome this minor setback," he told Ipswich's website.
Dyer played for Newcastle between 1999 and 2007 before joining West Ham United. He was capped 33 times by England.