Kidney disease, also known as chronic kidney failure, is the gradual loss of kidney function. The kidney filters water and excess fluids from the blood to the urine. Chronic kidney disease can cause increased levels of fluids or waste in the body and, in advanced stages, can be dangerous. Symptoms differ in every stage of disease and commonly include nausea, vomiting, loss of appetite, fatigue and weakness. Depending on its underlying cause, kidney disease can be treated by controlling symptoms, reducing complications and slowing disease progression. Dialysis or kidney transplant is necessary in late-stage kidney disease.