Hemolytic Uremic Syndrome

Hemolytic uremic syndrome usually begins with diarrhea and vomiting that contains blood. In addition, to these the following signs and symptoms are also present:

• Stools contain blood
• Fever
• Lethargy
• Passing out blood in urine or very less urinary output
• Weakness 
• Irritability
• Confusion
• Pain in the abdomen
• Development of swelling in the arms, feet and face
• Pallor
• Jaundice
• Bruising

In the later stages, affected individuals may also experience seizures, though this is very rare.

The following diagnostic procedures would be done to confirm HUS:

• Blood tests are carried out to study platelet count, level of creatinine and RBC count. Low levels of RBCs, low platelet count and elevated levels of creatinine all point towards onset of HUS.
• Peripheral blood smear examination by microscopy will reveal schistocytes as a marker of hemolysis among red blood cells in HUS [8].
• Stool sample will be analyzed to check for presence of bacteria and further analysis would also be done to determine the pathogenic strain.
• Urine analysis would determine the presence of blood and protein in urine.
• A urine protein test is also a necessity to evaluate the levels of protein excreted in urine.

In addition to the above mentioned tests, other tests include a kidney biopsy and blood clotting tests for differential diagnosis.

Patients with HUS require immediate hospitalization. The following are the treatment methods administered to stabilize the condition of the patient:

• Transfusions of red blood cells and platelets.
• Plasma exchange [9]
• Dialysis is done as there is acute renal failure. It is a temporary treatment method which is carried out until the kidney restores its normal functioning. If there is severe damage to the kidney or signs of chronic failure are noticed then kidney transplant may be necessary.
• Patient is given medications such as corticosteroids.
• Antibiotics may only be used when HUS patients are undergoing septicemia [10].

The prognosis of HUS is very favorable when appropriate treatment regime is initiated. About 70 – 80% children completely recover after treatment. Recovery period in children is faster as compared to adults.

Complications

The possible complications of HUS include the following:

• Hemolytic anemia due to destruction of red blood cells.
• High blood pressure
• Kidney failure
• Uremia
• Thrombocytopenia characterized by extremely low platelet counts.
• Problems of the nervous system
• Blood clotting problems
• Stroke
• Coma

Infections caused by E. coli O157:H7 lead to development of HUS [2]. Such a strain of E. coli causes gastrointestinal infections which precipitate by diarrhea and vomiting in affected children. In addition, other potent strains of E. coli like O111:H8, O103:H2, and O104:H4 have also been linked to HUS [3]. In adults, HUS is known to be triggered by the following factors:

• Medications like quinine [4], chemotherapy drugs, anti-platelet medications and immunosuppresants can cause HUS.
• Pregnant women are more prone to develop HUS [5].
• Individuals with infectious diseases such as H1N1 influenza A virus and HIV/AIDS are likely to suffer from HUS [6]. 
• Heredity can also play foul in causation of specific type of HUS known as atypical hemolytic uremic syndrome. 

Incidence of HUS peaks during the summer season and majorly affects children. It has been estimated that in United States, for children below 5 years of age, the prevalence of HUS per year has been recorded to be 6.1 cases per 100,000 population.

Hemolytic uremic syndrome is classified under two categories on the basis of its causative agent: Typical HUS and atypical HUS. In the former category, the development of the disease occurs due to toxins produced by E. coli O157:H7 and in the atypical variety, infections are not the cause. It can occur either due to genetic defect or can be sporadic in nature.

Once the pathogenic bacteria E. coli O157:H7 gains entry into the body, it produces Shiga toxin which binds with the epithelial cells lining the gut. Following this event, series of unfavorable reactions are triggered that cause destruction of red blood cells. The destroyed red blood cells then clog the filtering system in the kidney causing acute renal failure. This may further be aggravated by the loss of vascular endothelial growth factor (VEGF) in autoimmune diseases resulting to renal microvascular angiopathies [7].

Food borne cases of HUS can be prevented by following certain simple steps to avoid falling prey to these illnesses. They include:

• Appropriately cook raw meat and avoid consumption of such high risk foods on open food stalls.
• Raw food should not share the same platform with cooked food. Keep them separately.
• Hands should be thoroughly washed prior to cooking and eating.
• It is also necessary to wash and disinfect all raw produce before cooking them.
• Sanitization of the cooking surface prior to cooking should be done.

Hemolytic uremic syndrome (HUS) is a disease that causes sudden kidney failure due to destruction of the red blood cells (RBCs). The kidney failure is a temporary condition and functioning of the kidneys gets normal after rigorous treatment regime.

HUS remains to be the most common cause of acute renal failure in children [1]. Children who contract Escherichia coli (E. coli) infection fall prey to HUS. The disease usually begins with bloody diarrhea and finally causes destruction of the red blood cells that eventually block the filtering system. Such a condition causes sudden kidney failure. With prompt diagnosis and appropriate treatment regime, majority of the children completely recover from the condition.

Definition

Hemolytic uremic syndrome (HUS) is characterized by acute renal failure due to destruction of red blood cells usually as a result of severe infection due to E coli O157:H7. Such a condition commonly strikes the children; however it can also affect adults. Contaminated raw produce, water and uncooked meat products are the source of infections.

Cause

HUS occurs due to gastrointestinal infection caused by pathogenic strain of E. coli. In addition, other causes include certain medications, infectious diseases that affect the immune system and heredity factors.

Symptoms

Symptoms of HUS include bloody diarrhea, vomiting, anemia, blood in urine, decreased urinary output, fatigue, lethargy, confusion, pallor, irritability, edema and fever.

Diagnosis

Blood tests to detect levels of RBCs, platelets and total blood count forms the preliminary diagnostic procedures for detecting HUS. Urine analysis and stool culture are some of the additional tests that are done for confirming the disease condition.

Treatment

Patient is hospitalized immediately to ease the signs and symptoms. Acute renal failure is treated through temporary dialysis and the patient is also given transfusions of platelets and red blood cells.

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