Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Kidney Failure

What Is It?

In kidney failure, the kidneys lose their ability to filter enough waste products from the blood and to regulate the body's balance of salt and water. Eventually, the kidneys slow their production of urine, or stop producing it completely. Waste products and water accumulate in the body. This can lead to a potentially life-threatening overload of fluids (such as congestive heart failure), a dangerous accumulation of waste products in the blood, and extreme changes in blood chemistry that eventually can affect the function of the heart and brain. There are three types of kidney failure (also called renal failure). They are:

• Acute renal failure — Kidney function stops or is abruptly reduced because of a sudden illness, a medication or medical condition that causes one of the following:

  • A severe drop in blood pressure or an interruption in the normal blood flow to the kidneys, which can occur during major surgery, severe burns with fluid loss through burned skin, massive bleeding (hemorrhage) or a heart attack that severely affects heart function. Blood clots that travel to the kidney also can cause acute kidney failure.

  • Direct damage to kidney cells or to the kidneys' filtering units, which can be caused by inflammation in the kidneys, toxic chemicals, medications, contrast dye used for computed tomography (CT) scans and certain procedures (such as angiograms) that are guided by x-ray, and infections.

  • Blocked urine flow from the kidney, which can occur because of obstructions outside the kidney, such as kidney stones, bladder tumors or an enlarged prostate.

• Chronic renal failure — Kidney function gradually declines, usually over a period of years. It is most commonly caused by illnesses such as diabetes, uncontrolled high blood pressure or chronic kidney inflammation. Examples of conditions that cause inflammation in the kidney include glomerulonephritis and pyelonephritis. Chronic renal failure also can occur because of long-term exposure to lead, mercury or certain drugs, especially painkillers. Some forms of chronic renal failure run in families, so your doctor will ask you about family members' medical problems.

• End-stage renal disease — This also is called end-stage renal failure. This occurs when kidney function has deteriorated to the point that if dialysis treatments do not begin, the person will die. This is usually the end result of longstanding chronic renal failure, but occasionally, it also follows acute renal failure.