Inadequate renal function caused by deficient excretion of waste products, finally resulting in uraemia. A distinc- tion is made between acute and chronic kidney failure; the acute form is usually the result of acute necrosis of the kidney tubules or suddenly reduced blood circulation in the kidneys, because of low blood pressure, for example, or shock, or sometimes by blockage of both ureters. Blockage of one ureter does not usually cause kidney failure. The symptoms are a sudden reduction in urine production (anuria), associated with oedema, and also loss of appetite, nausea and listlessness. Recovery is usually spontaneous after a few days or weeks. Uraemia can occur very quickly in the initial phase, so renal dialysis (kidney machine) may have to be used. Chronic kidney failure often builds up slowly over the years. The most important cause is gradual kidney tissue decline caused by such conditions as chronic glomerulonephritis, chronic pyelitis, kidney cysts and disorders such as diabetes mellitus, gout, amyloidosis or rheumatic disorders. Chronic kidney failure can be associated with increased urine production, because the kidney is unable to concentrate the urine; nevertheless uraemia can still occur, likewise anaemia.