Acute kidney failure

Definition

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

Alternative Names

Kidney failure; Renal failure; Renal failure - acute; ARF; Kidney injury - acute

Causes, incidence, and risk factors

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

• Acute tubular necrosis (ATN)
• Autoimmune kidney disease, including:
  • Acute nephritic syndrome
  • Interstitial nephritis
• Decreased blood flow due to very low blood pressure, which can result from:
  • Burns
  • Dehydration
  • Hemorrhage
  • Injury
  • Septic shock
  • Serious illness
  • Surgery
• Disorders that cause clotting within the kidney's blood vessels:
  • Hemolytic-uremic syndrome
  • Idiopathic thrombocytopenic thrombotic purpura (ITTP)
  • Malignant hypertension
  • Transfusion reaction
  • Scleroderma
• Infections that directly injury the kidney such as:
  • Acute pyelonephritis
  • Septicemia
• Pregnancy complications, including:
  • Placenta abruptio
  • Placenta previa
• Urinary tract obstruction

Symptoms

• Bloody stools
• Breath odor
• Brusing easily
• Changes in mental statusor mood
• Decreased appetite
• Decreased sensation, especially in the hands or feet
• Fatigue
• Flank pain (between the ribs and hips)
• Hand tremor
• High blood pressure
• Metallic taste in mouth
• Nausea or vomiting, may last for days
• Nosebleeds
• Persistent hiccups
• Prolonged bleeding
• Seizures
• Slow, sluggish movements
• Swelling - generalized (fluid retention)
• Swelling of the ankle, feet, and leg swelling
• Urination changes:
  • Decrease in amount of urine
  • Excessive urination at night
  • Urination stops completely

Signs and tests

Many patients have generalized swelling caused by fluid retention. The doctor may hear a heart murmur, crackles in the lungs, or signs of inflammation of the lining of the heart when listening to the heart and lungs with a stethoscope.

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

• BUN
• Creatinine clearance
• Serum creatinine
• Serum potassium
• Urinalysis

A kidney or abdominal ultrasound is the preferred test for diagnosing kidney failure, 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. Arterial blood gas and blood chemistries may show metabolic acidosis.

Treatment

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. Your diet may need to 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.

Calcium, glucose/insulin, or potassium will be given through a vein to help avoid dangerous increases in blood potassium levels.

Dialysis may be needed, and can make you feel better. It is not always necessary, but it can save your life if your potassium levels are dangerously high. Dialysis will also be used if your mental status changes, you stop urinating, develop pericarditis, retain too much fluid, or cannot eliminate nitrogen waste products from your body.

Support Groups

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

Expectations (prognosis)

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

In some cases, chronic renal failure or end-stage renal disease may develop. Death 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.

Complications

• Chronic (long-term) kidney failure
• Damage to the heart or nervous system
• End-stage kidney disease
• High blood pressure
• Loss of blood in the intestines

Calling your health care provider

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

Prevention

Treating disorders such as high blood pressure can help prevent acute kidney failure.

References

Clarkson MR, Friedewald JJ, Eustace JA, Rabb H. Acute Kidney Injury. In: Brenner BM, ed. Brenner: Brenner and Rector's The Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap. 29.