failure occurs when illness, infection, or injury
damages the kidneys. Temporarily, the kidneys cannot
adequately remove fluids and wastes from the body or
maintain the proper level of certain kidney-regulated
chemicals in the bloodstream.
The kidneys are the body's natural filtration system.
They perform the critical task of processing
approximately 200 quarts of fluid in the bloodstream
every 24 hours. Waste products like urea and toxins,
along with excess fluids, are removed from the
bloodstream in the form of urine. Kidney (or renal)
failure occurs when kidney functioning becomes impaired.
Fluids and toxins begin to accumulate in the
bloodstream. As fluids build up in the bloodstream, the
patient with acute kidney failure may become puffy and
swollen (edematous) in the face, hands, and feet. Their
blood pressure typically begins to rise, and they may
experience fatigue and nausea.
Unlike chronic kidney failure, which is long term and
irreversible, acute kidney failure is a temporary
condition. With proper and timely treatment, it can
typically be reversed. Often there is no permanent
damage to the kidneys. Acute kidney failure appears most
frequently as a complication of serious illness, like
heart failure, liver failure, dehydration, severe burns,
and excessive bleeding (hemorrhage). It may also be
caused by an obstruction to the urinary tract or as a
direct result of kidney disease, injury, or an adverse
reaction to a medicine.
Causes and symptoms
Acute kidney failure can be caused by many different
illnesses, injuries, and infections. These conditions
fall into three main categories: prerenal,
postrenal, and intrarenal conditions.
Prerenal conditions do not damage the kidney, but can
cause diminished kidney function. They are the most
common cause of acute renal failure, and include
- septicemia, or sepsis
- heart failure
- liver failure
Postrenal conditions cause kidney failure by
obstructing the urinary tract. These conditions include:
- inflammation of the prostate gland in men
- enlargement of the prostate gland (benign
- bladder or pelvic tumors
- kidney stones (calculi)
Intrarenal conditions involve kidney disease or
direct injury to the kidneys. These conditions include:
- lack of blood supply to the kidneys (ischemia)
- use of radiocontrast agents in patients with
- drug abuse or overdose
- long-term use of nephrotoxic medications, like
certain pain medicines
- acute inflammation of the glomeruli, or filters,
of the kidney (glomerulonephritis)
- kidney infections (pyelitis or pyelonephritis).
Common symptoms of acute kidney failure include
- anemia. The kidneys are responsible for
producing erythropoietin (EPO), a hormone that
stimulates red blood cell production. If kidney
disease causes shrinking of the kidney, red blood
cell production is reduced, leading to anemia.
- bad breath or bad taste in mouth. Urea in the
saliva may cause an ammonia-like taste in the mouth.
- bone and joint problems. The kidneys produce
vitamin D, which helps the body absorb calcium and
keeps bones strong. For patients with kidney
failure, bones may become brittle. In children,
normal growth may be stunted. Joint pain may also
occur as a result of high phosphate levels in the
blood. Retention of uric acid may cause gout.
- edema. Puffiness or swelling in the arms, hands,
feet, and around the eyes.
- frequent urination.
- foamy or bloody urine. Protein in the urine may
cause it to foam significantly. Blood in the urine
may indicate bleeding from diseased or obstructed
kidneys, bladder, or ureters.
- headaches. High blood pressure may trigger
- hypertension, or high blood pressure. The
retention of fluids and wastes causes blood volume
to increase. This makes blood pressure rise.
- increased fatigue. Toxic substances in the blood
and the presence of anemia may cause the patient to
- itching. Phosphorus, normally eliminated in the
urine, accumulates in the blood of patients with
kidney failure. An increased phosphorus level may
cause the skin to itch.
- lower back pain. Patients suffering from certain
kidney problems (like kidney stones and other
obstructions) may have pain where the kidneys are
located, in the small of the back below the ribs.
- nausea. Urea in the gastric juices may cause
Kidney failure is diagnosed by a doctor. A
nephrologist, a doctor that specializes in the kidney,
may be consulted to confirm the diagnosis and recommend
treatment options. The patient that is suspected of
having acute kidney failure will have blood and urine
tests to determine the level of kidney function. A blood
test will assess the levels of creatinine, blood urea
nitrogen (BUN), uric acid, phosphate, sodium, and
potassium. The kidney regulates these agents in the
blood. Urine samples will also be collected, usually
over a 24-hour period, to assess protein loss and/or
Determining the cause of kidney failure is critical
to proper treatment. A full assessment of the kidneys is
necessary to determine if the underlying disease is
treatable and if the kidney failure is chronic or acute.
X rays, magnetic resonance imaging (MRI), computed
tomography scan (CT), ultrasound, renal biopsy, and/or
arteriogram of the kidneys may be used to determine the
cause of kidney failure and level of remaining kidney
function. X rays and ultrasound of the bladder and/or
ureters may also be needed.
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