Urea - kidney failure - causes a build up of urea in the blood as the kidney eliminates urea from the blood into the bladder. The specific effects of Urea on cell metabolism are probably numerous as the symptoms: anorexia and lethargy, and late symptoms can include decreased mental acuity and coma. Other symptoms include fatigue, nausea, vomiting, cold, bone pain, itch, shortness of breath, and seizures.
Being a metabolic waste product, it certainly would interfere with and inhibit any enzyme that produced urea - the Urea cycle in particular. Its clear that uremia is ultimately associated with cell death, oxidative stress, some cell signalling and proliferation.