Atypical HUS in Adults

Thrombotic microangiopathy due to dysregulation of the complement system.

Written by: Saygı Hospital Health Guide Editorial Board

Last updated: June 10, 2026

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 HUS in Adults?

Atypical hemolytic uremic syndrome (aHUS) is a rare and severe thrombotic microangiopathy in adults caused by uncontrolled activation of the alternative complement pathway. Genetic complement defects (CFH, CFI, MCP, C3, CFB) or autoantibodies are the underlying causes.

Microangiopathic hemolytic anemia, thrombocytopenia and acute kidney injury constitute the classic triad. Multi-organ involvement (heart, brain, gastrointestinal system) may occur. Mortality and end-stage renal disease risk are high if untreated.

Differential diagnosis includes thrombotic thrombocytopenic purpura (TTP, ADAMTS13 activity <10%) and Shiga-toxin-producing E. coli HUS. Eculizumab and ravulizumab (anti-C5 monoclonal antibodies) are first-line targeted therapy.

Symptoms

Severe weakness and pallor

Acute kidney injury

Bruising and thrombocytopenia

Hypertension

Neurological findings (confusion)

Petechiae

Heart failure findings

Risk Factors

Complement gene mutations (CFH, CFI, MCP)

Anti-CFH autoantibodies

Pregnancy and postpartum

Drugs (mitomycin, calcineurin inhibitors)

Family history

Autoimmune disease

When to See a Doctor?

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

Acute weakness and pallor
Sudden decrease in urine output
Bruising on the skin
Sudden hypertension
Confusion
Acute kidney injury laboratory findings

Treatment Methods

Eculizumab/ravulizumab (anti-C5)

Plasma exchange (early if TTP not excluded)

Renal replacement therapy

Vaccines for meningococcal infection

Long-term follow-up and recurrence monitoring

Genetic counseling

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 Appointment Contact 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.