Your kidneys are the key organs in the complex filtration system that removes excess fluid and waste material from the blood. Your kidneys receive blood through your renal arteries, which branch off the main artery (the abdominal aorta) carrying oxygenated blood away from your heart. On entering the kidneys, blood is distributed through smaller and smaller vessels, finally reaching tiny capillary blood vessels arranged in tufts (glomeruli).
The glomeruli filter your blood, extracting fluid, waste and substances your body needs — sugar, amino acids, calcium and salts. These filtered materials then cross into tiny tubules, from which the bloodstream reabsorbs what the body can reuse. The rest is waste, which is excreted in your urine.
Although your kidneys are usually able to clear all the waste products your body produces, problems can occur if blood flow to your kidneys is disrupted, if the tubules or glomeruli become damaged or diseased, or if urine outflow is obstructed.
Chronic kidney failure is a gradual loss of your kidneys' filtering ability, usually due to high blood pressure or diabetes. When kidney function is seriously impaired, dangerous levels of fluid and waste can quickly accumulate in your body.
In the early stages of chronic kidney failure, you may have few signs or symptoms. Many people with chronic kidney failure don't realize they have a problem until their kidney function has decreased to less than 25 percent of normal.
The main goal of treatment of chronic kidney failure is to halt or delay progression of the disease, usually by controlling the underlying cause. Chronic kidney failure can progress to end-stage kidney disease, which is fatal without artificial filtering (dialysis) or a kidney transplant.