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.