A renal failure progresses the kidneys have a harder time removing excess solutes (sodium, potassium, phosphorus), fluid, acid (hydrogen ions) and blood urea nitrogen. Retention of BUN results in a clinical state called ‘uremia’. Manifestations of this include fatigue, weakness, nausea, poor appetite, reduced concentration, confusion and lethargy. There is not a specific BUN number after which symptoms start to develop. It varies amongst different individuals. If one is uremic they would require a form of renal replacement therapy such as hemodialysis, peritoneal dialysis, or renal transplantation.