The information on this website is not intended for diagnosis or treatment. Please consult your physician for health concerns.

+90 850 321 50 00

Atypical Hemolytic Uremic Syndrome (aHUS)

Rare complement-mediated thrombotic microangiopathy causing kidney failure, hemolysis, and thrombocytopenia

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Dahiliye (İç Hastalıkları) department. Book Appointment →

What is Atypical Hemolytic Uremic Syndrome (aHUS)?

aHUS is a complement-mediated form of thrombotic microangiopathy, distinct from typical HUS (Shiga toxin-mediated, post-diarrheal).

Pathophysiology: dysregulation of alternative complement pathway leading to endothelial damage and microthrombosis in kidney and other organs.

60-70 percent of cases have identifiable genetic mutations: CFH, CFI, MCP, C3, CFB, THBD, DGKE.

Triggers in genetically predisposed: infections, pregnancy, surgery, drugs, transplantation.

Affects all ages but childhood-onset and adult-onset forms have distinct genetics and outcomes.

Without treatment, mortality up to 25 percent and ESRD in 50 percent within first year.

Symptoms

Triad: microangiopathic hemolytic anemia, thrombocytopenia, acute kidney injury.
Fatigue, pallor, jaundice from hemolysis.
Bruising, petechiae, mucosal bleeding from thrombocytopenia.
Hypertension, edema, oliguria/anuria from kidney involvement.
Extra-renal manifestations: neurologic (seizures, stroke, encephalopathy), cardiovascular (myocardial infarction, cardiomyopathy), GI (ischemia), pulmonary.
Recurrence after kidney transplantation in 60-90 percent without prophylaxis.

Risk Factors

Genetic complement gene mutations (CFH, CFI, MCP, C3, CFB).
Anti-CFH autoantibodies (typically children, treated with immunosuppression).
Pregnancy (especially postpartum), oral contraceptives.
Infections (upper respiratory, gastroenteritis), bacterial endotoxin.
Drug-induced: calcineurin inhibitors (tacrolimus, cyclosporine), VEGF inhibitors, gemcitabine, mitomycin.
Solid organ or stem cell transplantation, malignancy, autoimmune disease (SLE, antiphospholipid syndrome).

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Acute kidney injury with hemolysis (elevated LDH, low haptoglobin, schistocytes) and thrombocytopenia.
  • Family history of aHUS or unexplained kidney failure.
  • Postpartum onset of MAHA, AKI, thrombocytopenia.
  • TMA in setting of complement-amplifying conditions (infection, surgery, pregnancy).
  • Recurrence of TMA after kidney transplantation.
  • Differentiation from TTP (ADAMTS13 < 10 percent), Shiga toxin-HUS (stool culture/PCR), drug-induced TMA.

Treatment Methods

01
Eculizumab (Soliris) - anti-C5 monoclonal antibody, first-line; rapid initiation crucial to prevent ESRD.
02
Pre-treatment: meningococcal vaccination (groups A, B, C, W, Y) at least 2 weeks before; prophylactic antibiotics if urgent.
03
Ravulizumab (Ultomiris) - long-acting C5 inhibitor, 8-week dosing intervals, increasingly used.
04
Plasma exchange/infusion - historical first-line, less effective; bridge to eculizumab when complement diagnosis pending.
05
Supportive care: blood pressure control, dialysis if needed, transfusions for severe anemia.
06
Genetic testing for CFH, CFI, MCP, C3, CFB, anti-CFH antibodies; counseling for family members.
07
Immunosuppression for anti-CFH antibody form (steroids, rituximab, plasma exchange).
08
Kidney transplantation feasible with prophylactic eculizumab; combined liver-kidney transplant for high-risk CFH/CFI mutations.

Which Department to Visit?

You can visit our Dahiliye (İç Hastalıkları) department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

Learn About Dahiliye (İç Hastalıkları) Department

Let us help you

You can make an appointment with our specialists or contact us for your concerns.

Book AppointmentContact Us

Related Health Topics

Other articles from the same department you may want to explore.

Anaemia

Dahiliye (İç Hastalıkları)

Anaemia is a low haemoglobin level that reduces oxygen delivery, causing fatigue, pallor, and shortness of breath. It is not a disease itself but a sign of many underlying conditions. Most cases are correctable with appropriate diagnosis and treatment.

Iron Deficiency Anaemia

Dahiliye (İç Hastalıkları)

Iron deficiency anaemia develops when dietary intake, absorption, or losses create an iron shortfall, most often affecting women and children. Identifying the underlying cause is the core of management, alongside iron replacement.

Vitamin B12 Deficiency

Dahiliye (İç Hastalıkları)

Vitamin B12 deficiency can cause megaloblastic anaemia, neurological symptoms, and cognitive impairment. Early treatment with intramuscular or oral B12 largely prevents irreversible complications.

Hypertension (High Blood Pressure) Management

Dahiliye (İç Hastalıkları)

Hypertension is often called the silent killer because it progresses symptom-free for years and can damage the heart, brain, kidneys, and eyes. Regular monitoring, lifestyle change, and evidence-based drug therapy dramatically reduce cardiovascular risk.

Chronic Kidney Disease

Dahiliye (İç Hastalıkları)

Chronic kidney disease is one of the most common complications of chronic conditions such as diabetes and hypertension, and can be silent in its early stages.

Hepatitis B (HBV)

Dahiliye (İç Hastalıkları)

Hepatitis B is a DNA virus infection causing acute and chronic hepatitis with risk of cirrhosis and hepatocellular carcinoma; diagnosis integrates HBsAg, HBeAg, anti-HBc, and HBV DNA with management based on disease phase using nucleos(t)ide analogues (entecavir, tenofovir) and universal infant vaccination.

Hepatitis C (HCV)

Dahiliye (İç Hastalıkları)

Hepatitis C is an RNA virus causing chronic hepatitis that may progress to cirrhosis and hepatocellular carcinoma; modern direct-acting antiviral (DAA) pangenotypic regimens (sofosbuvir/velpatasvir, glecaprevir/pibrentasvir) achieve sustained virologic response over 95% in 8–12 weeks with universal adult screening and cure for nearly all patients.

Fatty Liver Disease

Dahiliye (İç Hastalıkları)

Non-alcoholic fatty liver disease (NAFLD) is closely related to obesity and metabolic syndrome and is largely reversible with early treatment.

Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.