Atypical hemolytic uremic syndrome (aHUS) is a rare but serious condition in which the immune system mistakenly attacks the lining of blood vessels, leading to the formation of small blood clots. These clots can reduce blood flow to vital organs, particularly the kidneys, causing significant damage. Early diagnosis and treatment are critical for managing this potentially life-threatening disorder. Learn more about the causes, symptoms, and treatment of aHUS.*

Causes and Triggers of aHUS

Atypical hemolytic uremic syndrome is primarily linked to genetic mutations that disrupt normal immune function and affect the complement system, a part of the immune system responsible for fighting infections. 

These mutations alone are not usually enough to cause the disease; aHUS often requires an external trigger to manifest. Common triggers include:

• Pregnancy,
• Cancer,  
• Infections, and 
• Certain medications like:
  • Chemotherapy agents, 
  • Immunosuppressants, and 
  • Oral contraceptives.

Environmental factors play a significant role in triggering the onset of aHUS.

Symptoms of aHUS

The symptoms of aHUS can vary and often develop gradually, making the condition difficult to diagnose early. Common symptoms include:

• Fatigue  
• Paler than usual skin 
• Nausea 
• Reduced urine output 
• Blood in the urine 
• High blood pressure 
• Edema (swelling) 

In some cases, patients may also experience neurological symptoms, such as confusion, although these are less frequent.

Diagnosis and Treatment of aHUS

Atypical hemolytic uremic syndrome is distinct from typical hemolytic uremic syndrome, which is usually associated with diarrhea and caused by an E. coli infection. 

Diagnosing aHUS requires careful evaluation of symptoms, and the use of various diagnostic tests. Healthcare providers typically diagnose a person with aHUS when the patient exhibits three critical conditions simultaneously:

• Microangiopathic hemolytic anemia, 
• Thrombocytopenia, and 
• Acute kidney injury (AKI). 

The diagnostic tools can include:

• Blood tests, 
• Genetic testing, 
• Kidney biopsy, and 
• Imaging studies. 

Treatment varies depending on the severity of the condition. Mild cases may be managed with supportive care, while severe cases may require therapeutic plasma exchange, dialysis, or even kidney transplantation. 

The introduction of the drug eculizumab has significantly improved the prognosis for aHUS patients, reducing the risk of end-stage kidney disease and improving overall patient outcomes.

Takeaways

Atypical hemolytic uremic syndrome is a complex and life-threatening condition that requires prompt attention and management. Understanding its causes, symptoms, and treatment options is crucial for effective care. 

Advances in treatment, particularly with eculizumab, have significantly improved the outlook for those diagnosed with aHUS, making early diagnosis and intervention more critical than ever.

*Cleveland Clinic. (2023, November 29). Atypical Hemolytic Uremic Syndrome. Retrieved from https://my.clevelandclinic.org/health/diseases/atypical-hemolytic-uremic-syndrome 

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