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Blood and immune system diseases

Atypical hemolytic uremic syndrome (aHUS)

A rare disease in which clots form in small blood vessels. It mainly affects the kidneys. Anemia, low blood platelets and kidney failure are seen.

Not part of the panel of Türkiye's National Newborn Screening Programme (heel-prick test). Source

Orphanet has a guideline for emergency doctors for this disease (language: French). See on Orphanet

Prepare an emergency card

This page is translated from the Turkish original.

This disease is followed through the “Blood and immune system diseases” group.

Understanding the disease

This section has not yet been reviewed by a physician. It summarises patient information from sources such as MedlinePlus, Orphanet and the NHS in plain language. The disease can differ from person to person; talk to your doctor about diagnosis and treatment.

What happens in this disease?

The complement system is a part of the immune system that attacks germs. In aHUS, this system works out of control. It damages the inner lining of the blood vessels, and small clots form. The clots mainly affect the blood vessels of the kidneys. The brain, heart, lungs and gut can also be affected. An attack is often triggered by an infection or pregnancy.

Which symptoms can occur?

The disease can begin at any age. The first symptoms may be vague.

  • Tiredness, irritability and weakness
  • Paleness, yellowing and shortness of breath
  • Easy bruising and bleeding
  • Blood and protein in the urine
  • High blood pressure
  • Sudden decline in kidney function
  • Symptoms related to the brain, heart or gut

How is it diagnosed?

Blood tests show anemia, breakdown of blood and low platelets. Kidney tests and a urine examination are done. To tell it apart from typical HUS, the stool is tested for bacteria that cause diarrhea. Genetic tests and antibody tests help with the diagnosis.

Treatment and care

There are approved treatments specific to the disease that block the complement system. A meningitis vaccine is given before these treatments. Plasma exchange and plasma infusion are methods that have long been used. If the kidneys fail, dialysis may be needed. Some people may have a kidney transplant. Genetic testing is recommended before a transplant. The doctor who follows the disease decides which treatment is suitable.

For the family: inheritance and genetic counselling

In most patients, no one else in the family is affected. A gene change creates a tendency toward the disease, but on its own it is usually not enough. When it runs in a family, it is mostly passed on through dominant inheritance. In this case, a parent who carries the gene has a 1 in 2 chance of passing it to each child. Not everyone who carries the gene becomes ill. Less often, recessive inheritance is also seen. Genetic counselling helps in understanding the risk.

Source: MedlinePlus Genetics: Atypical hemolytic-uremic syndrome · NORD: Atypical Hemolytic Uremic Syndrome

Key facts

How common is it?
Prevalence: 1-9 per 100 000 (Europe)
When does it usually start?
Any age

These facts are taken from Orphanet and MedlinePlus records (last checked: October 7, 2026). Frequency values are approximate ranges.

You are not alone: patient associations in Türkiye

Non-profit patient and family organizations in Türkiye working on this disease or disease group. Links are for information; Doktorclub is not affiliated with these organizations and does not endorse them.

We could not find a patient association specific to this disease.

For all rare diseases: Nadir Hastalıklar Federasyonu

Support and help

Doktorclub does not diagnose, recommend treatments or refer you to hospitals or doctors. These pages are meant to help you talk with your doctor.

News about aHUS

Clinical trials (ClinicalTrials.gov)

A clinical trial is a regulated study that tests whether a new treatment is safe and whether it works, in patients who volunteer. Most trials look for a certain age, genetic change and health condition. Taking part is voluntary.

This list is not a treatment recommendation. Treatments tested in phase 1–3 trials are investigational (experimental): their efficacy and safety have not yet been proven and they are not approved treatments. Taking part depends on each trial’s criteria and a physician’s assessment; the first step is to talk to the doctor who manages your care.

Questions you can ask your doctor

  • Could this trial be suitable for us?
  • If we take part, how would current treatment and check-ups be affected?
  • Where does the trial take place, and how are travel and accommodation handled?
  • What happens if we want to leave the trial?

ClinicalTrials.gov lists 8 active interventional studies for this disease. 5 are recruiting now; 3 have sites in Türkiye. Last checked: October 7, 2026.

Selected records (studies with a site in Türkiye first):

See all studies on ClinicalTrials.gov · Joining clinical trials

Blood and immune system diseases: other news

Medical codes (for talking with your doctor and finding sources)

These codes identify the disease in international classifications and databases. They can help when you talk with your doctor or look for reliable sources.

Orphanet code: ORPHA:2134

No separate ICD-11 code; WHO classifies this disease under: 3A10.Y

Codes checked against WHO ICD-11 and Orphanet on October 7, 2026.

This page provides general information and does not replace diagnosis or treatment. Talk to your doctor about symptoms, diagnosis and treatment.

The information on these pages is for general information only and does not replace medical advice. Talk to your doctor about diagnosis and treatment decisions. In an emergency in Türkiye, call 112.

Every update is based on an open source and labeled with its level of evidence. No advertising and no drug brand names. Our scientific principles

This page was translated from Turkish by the Doktorclub editorial team.