Wolf-Hirschhorn syndrome

Disease Description (Causes and Symptoms)

Hemolytic Uremic Syndrome (HUS) is a group of disorders characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure (acute kidney injury), which are major findings belonging to the tetrad.
Main causes and pathophysiology:

• Typical (diarrhea-associated, D+ HUS): Occurs after infection with Shiga toxin from enterohemorrhagic Escherichia coli (E. coli O157:H7, etc.) or Shigella. The toxin damages vascular endothelial cells, causing microvascular thrombosis and hemolysis. It is most common in children aged 4 years or younger.
• Atypical (diarrhea-independent, aHUS): Complement activation caused by various factors, including dysregulation of the complement system (especially the alternative pathway; genetic mutations or acquired abnormalities), medications, pregnancy, autoimmune diseases (e.g., SLE and antiphospholipid antibodies), transplantation, and cancer, leading to endothelial damage. Some bacterial causes, such as pneumococcal infection, are also possible.
  Main symptoms:
• Gastrointestinal symptoms (typical): Diarrhea (sometimes bloody), abdominal pain, fever, and vomiting → renal failure and signs of hemolysis develop 1–2 weeks later
• Systemic: Pallor and fatigue (anemia), hematuria, decreased urine output, and edema (decreased kidney function), hypertension, purpura and bruising, jaundice, and hepatomegaly (rarely)
• In severe cases, neurological symptoms such as confusion and seizures may occur

Treatment Methods and Precautions

The goals of treatment are to preserve kidney function, stabilize electrolytes, body fluids, and blood pressure, prevent complications, and treat the underlying cause.

Standard treatment and management:

• Supportive care (the basis of treatment for typical HUS)
  • Correction of fluid, electrolyte, and acid–base balance; monitoring of fluid status
  • Blood pressure management (antihypertensive medication if necessary)
  • Renal replacement therapy (dialysis/hemodialysis or peritoneal dialysis) for uremia, electrolyte abnormalities, edema, or fluid overload
  • Red blood cell transfusion in cases of severe anemia (when bleeding or severe symptoms are present)
  • Platelet transfusion is generally avoided based solely on a low platelet count (used only when bleeding is present or an invasive procedure is necessary)
• Medications and special treatments
  • Typical (Shiga toxin-related) HUS: Antibiotics are generally not recommended (some antibiotics may worsen symptoms by causing toxin release). In cases of pneumococcal HUS, appropriate antibiotic use is necessary.
  • Atypical HUS (complement-mediated): Complement C5 inhibitors (e.g., eculizumab or subsequent agents) are the standard treatment, used depending on severity and cause — because of the risk of meningococcal infection, preventive meningococcal vaccination and antibiotic prophylaxis should be considered when these drugs are used.
  • Plasma exchange: Has been used in some atypical and severe cases, but complement inhibitors are often prioritized. Plasma exchange may be considered depending on the clinical situation.
• Long-term follow-up and prevention
  • Long-term monitoring of kidney function, proteinuria, and blood pressure (needed for several years)
  • Because aHUS has a risk of recurrence, genetic testing and consultation with a specialist should be considered, especially when there is a family history.

Precautions and self-management:

• If typical HUS is suspected, do not take antibiotics (particularly including some beta-lactam antibiotics) on your own; consult the treating physician.
• Anticoagulants, antiplatelet agents, and fibrinolytic agents may increase the risk of bleeding and are generally contraindicated or should be used cautiously.
• Fever and respiratory symptoms (when eculizumab is administered): Report them immediately and confirm that preventive vaccinations have been received.
• Check your weight, urine output, edema, and blood pressure frequently and visit a medical institution immediately if your condition worsens.

Checklist Before an Outpatient Visit (Examples of Items to Prepare and Records)

Items/documents to bring:

• List of currently taken medications (including doses and administration times) and recent prescriptions
• Past medical history (especially kidney disease, autoimmune disease, transplantation, and pregnancy history) and family history (kidney disease, abnormal bleeding, etc.)
• Recent test results, if available: CBC (anemia and platelets), serum creatinine and electrolytes, urinalysis, LDH, bilirubin, and haptoglobin (markers of hemolysis), and stool tests (culture and Shiga toxin PCR)
• Symptom records: Whether diarrhea occurred, its start date, whether there was bloody stool, changes in urine output, changes in weight and edema, whether fever or vomiting occurred, and neurological symptoms such as altered consciousness or seizures

Examples of information to provide to the doctor during an outpatient visit (including questions):

• The date symptoms began and how they have progressed (e.g., "When did the diarrhea start? Is there blood in the stool?")
• Changes in urine output (hourly and daily urine volume) and urine color (whether it is reddish or cloudy)
• Recently taken antibiotics or other medications, and vaccination history (especially meningococcal vaccination)
• Whether anyone in the family has had similar symptoms or a history of chronic renal failure

Examples of General Questions to Ask the Doctor

• What do you think is the cause of this condition? How do you distinguish typical HUS from atypical HUS?
• How impaired is my (or the patient's) kidney function currently? How likely is dialysis to be needed?
• What treatment options are recommended (supportive care, plasma exchange, complement inhibitors, etc.), and what are the advantages, disadvantages, and side effects of each treatment?
• What is the long-term prognosis (possibility of kidney function recovery and risk of recurrence), and what is the follow-up testing schedule?
• Is genetic testing (complement-related genetic testing) necessary? How much does it cost, and how long does testing take?

Examples of Disease-Specific Questions

• If diarrhea is the cause: "Have tests for Escherichia coli (O157:H7) or Shiga toxin been performed? If antibiotics should not be used, in what situations are there exceptions?"
• If atypical HUS is suspected: "Please let me know whether complement inhibitor treatment (eculizumab) is recommended and whether meningococcal vaccination and preventive measures are needed before treatment."

Potential permanent complications: chronic kidney disease (CKD), hypertension, proteinuria, chronic dialysis-dependent renal failure, the need for kidney transplantation, neurological damage, and, rarely, death (the mortality rate during the acute phase is generally less than 5%).

(The above information is general medical information; diagnosis and treatment for individual patients require consultation with the treating medical team.)