Hemolytic–uremic syndrome

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Hemolytic–uremic syndrome (HUS) is a condition characterized by the destruction of red blood cells, which leads to acute kidney failure. It is a serious condition that primarily affects children but can also occur in adults. HUS is often caused by an infection with certain strains of Escherichia coli (E. coli) bacteria, particularly the strain O157:H7.

Signs and Symptoms

The symptoms of HUS can vary but typically include:

• Hemolytic anemia: Destruction of red blood cells leading to fatigue, pallor, and shortness of breath.
• Thrombocytopenia: Low platelet count causing easy bruising, bleeding, and petechiae.
• Acute kidney injury: Reduced kidney function leading to decreased urine output, swelling, and high blood pressure.
• Gastrointestinal symptoms: Abdominal pain, vomiting, and bloody diarrhea.

Causes

HUS is most commonly triggered by an infection with Shiga toxin-producing E. coli (STEC). Other causes can include:

• Pneumococcal infection
• Certain medications
• Pregnancy
• Genetic mutations in complement regulatory proteins

Pathophysiology

The pathophysiology of HUS involves the following steps: 1. Infection with STEC leads to the production of Shiga toxin. 2. Shiga toxin enters the bloodstream and damages the endothelial cells lining the blood vessels. 3. This damage causes the formation of microthrombi, which leads to the destruction of red blood cells and platelets. 4. The damaged red blood cells clog the tiny blood vessels in the kidneys, leading to acute kidney injury.

Diagnosis

The diagnosis of HUS is based on clinical symptoms and laboratory tests, including:

• Complete blood count (CBC) showing hemolytic anemia and thrombocytopenia.
• Blood smear showing schistocytes (fragmented red blood cells).
• Elevated serum creatinine indicating kidney dysfunction.
• Stool culture to identify STEC infection.

Treatment

Treatment of HUS focuses on supportive care, including:

• Intravenous fluids to maintain hydration and electrolyte balance.
• Blood transfusions for severe anemia.
• Dialysis for patients with severe kidney failure.
• Plasma exchange in certain cases, especially atypical HUS.

Prognosis

The prognosis of HUS varies depending on the severity of the condition and the promptness of treatment. With appropriate care, many patients recover fully, although some may develop long-term kidney problems or other complications.

Prevention

Preventive measures include:

• Proper food handling and cooking to avoid E. coli infection.
• Good hygiene practices, such as regular handwashing.
• Avoiding unpasteurized dairy products and juices.

See Also

• Thrombotic thrombocytopenic purpura
• Escherichia coli
• Acute kidney injury
• Hemolytic anemia