Acute (sudden) kidney failure is the sudden loss of the ability of the kidneys to remove waste and concentrate urine without losing electrolytes.

There are many possible causes of kidney damage. They include:

• Decreased blood flow, which may occur with extremely low blood pressure caused by trauma, surgery, serious illnesses, septic shock, hemorrhage, burns, or dehydration
• Acute tubular necrosis (ATN)
• Infections that directly injury the kidney such as acute pyelonephritis or septicemia
• Urinary tract obstruction (obstructive uropathy)
• Autoimmune kidney disease such as interstitial nephritis or acute nephritic syndrome
• Disorders that cause clotting within the thin blood vessels of the kidney
  • Idiopathic thrombocytopenic thrombotic purpura (ITTP)
  • Transfusion reaction
  • Malignant hypertension
  • Scleroderma,
  • Hemolytic-uremic syndrome
  • Disorders of childbirth, such as bleeding placenta abruptio or placenta previa

• Decrease in amount of urine (oliguria)
• Urination stops (anuria)
• Excessive urination at night
• Ankle, feet, and leg swelling
• Generalized swelling, fluid retention
• Decreased sensation, especially in the hands or feet
• Decreased appetite
• Metallic taste in mouth
• Persistent hiccups
• Changes in mental status or mood
  • Agitation
  • Drowsiness
  • Lethargy
  • Delirium or confusion
  • Coma
  • Mood changes
  • Trouble paying attention
  • Hallucinations
• Slow, sluggish, movements
• Seizures
• Hand tremor (shaking)
• Nausea or vomiting, may last for days
• Brusing easily
• Prolonged bleeding
• Nosebleeds
• Bloody stools
• Flank pain (between the ribs and hips)
• Fatigue
• Breath odor
• High blood pressure

Examination and testing can help diagnose acute kidney failure and help rule out other problems that can affect kidney function.

Many patients have generalized swelling caused by fluid retention. The doctor will use a stethoscope to listen to the heart and lungs. A heart murmur, crackles in the lungs, inflammation of the lining of the heart (pericarditis), or other related to extra fluid may be heard.

The results of laboratory tests may change suddenly (within a few days to 2 weeks).

• Urine tests (urinalysis) may be abnormal.
• Serum creatinine, BUN, creatinine clearance, and serum potassium levels may increase.
• Arterial blood gas and blood chemistries may show metabolic acidosis.
• Kidney or abdominal ultrasound are preferred tests, but abdominal x-ray, abdominal CT scan, or abdominal MRI can tell if there is a blockage in the urinary tract.
• Blood tests may help reveal the underlying cause of kidney failure.

Once the cause is found, the goal of treatment is to restore kidney function and prevent fluid and waste from building up in the body while the kidneys heal. Usually, you have to stay overnight in the hospital for treatment.

The amount of liquid you eat (such as soup) or drink will be limited to the amount of urine you can produce. You will be told what you may and may not eat to reduce the build-up of toxins normally handled by the kidneys. This diet may be high in carbohydrates and low in protein, salt, and potassium.

You may need antibiotics to treat or prevent infection. Diuretics ("water pills") may be used to help the kidneys lose fluid.

It will be very important to avoid dangerous hyperkalemia (increased blood potassium levels) by using IV (intravenous) calcium, glucose/insulin, or potassium exchange resin (Kayexalate).

Dialysis may be needed, and can make you feel better. It is not always necessary, but it can save your life if your serum potassium is dangerously high. Dialysis will also be used if your mental status changes, your potassium level starts to rise, you stop urinating, develop pericarditis, become overloaded with fluid, or cannot eliminate nitrogen waste products from your body.

The stress of having an illness can often be helped by joining a support group where members share common experiences and problems. See kidney disease - support group. Your local hospital or dialysis center can probably give you information on local support groups.

While acute kidney failure is potentially life-threatening and may require intensive treatment, the kidneys usually start working again within several weeks to months after the underlying cause has been treated.

In cases where this does not happen, chronic renal failure or end-stage renal disease develops. Death can occur, but is most common when kidney failure is caused by surgery, trauma, or severe infection in someone with heart disease, lung disease, or recent stroke. Old age, infection, loss of blood from the intestinal tract, and progression of kidney failure also increase the risk of death.

• Loss of blood in the intestines
• Chronic (ongoing) kidney failure
• End-stage renal disease
• Damage to the heart or nervous system
• Hypertension (high blood pressure)

Call your health care provider if your urine output slows or stops or you have other symptoms of acute kidney failure.

Treating disorders such as high blood pressure can help prevent acute kidney failure. Unfortunately, prevention is not always possible.