What is aHUS?
aHUS (atypical hemolytic uremic syndrome) is a rare disease that causes too many blood clots to form in your blood vessels. Because these blood clots block regular blood flow to your kidneys, your kidneys are not able to get rid of waste in your body as well as they should. Over time, your kidneys become damaged, which can lead to kidney failure.
Besides kidney damage, the signs of aHUS include low red blood cell and platelet count. Most people with aHUS have all three signs of the disease; kidney damage, low red blood cell and low platelet count, but not everyone does.
The symptoms of aHUS usually happen in flare-ups. Flare-ups of aHUS are often started by a trigger in your body. Some flare-ups of aHUS can be mild, and will not affect your kidneys. During a severe flare-up, your kidneys may be damaged and can fail.
It is also possible to have chronic aHUS, meaning you have symptoms of the disease all the time instead of only during flare-ups.
Who can get aHUS?
You can get aHUS at any age. In children, aHUS happens in even amounts across genders. In adults, aHUS is more common in women because it is sometimes triggered by pregnancy.
Researchers are still trying to learn more about the disease and why people get it.
What causes aHUS?
In most cases, aHUS is related to gene mutations, coupled with a triggering event. Just having a gene mutation alone usually will not cause the disease. You need a gene mutation and a triggering event for a flare-up to start. Some examples of aHUS triggers are:
- Infections (from viruses and/or bacteria)
- Certain medicines
In other more rare cases, aHUS is related to the development of antibodies that attack your body’s own immune system. The reason some people develop these antibodies is unknown.
In aHUS cases where gene mutations and antibodies are not involved, the cause is not known. Many researchers think that cases of aHUS where the cause is unknown are linked to mutations in genes that have not yet been discovered.
What are the complications of aHUS?
Complications of aHUS are serious. aHUS causes the body to develop too many blood clots, which causes your blood to flow too slowly to important organs. Your blood flow can even be cut off completely. This can cause the following:
- Kidney damage or kidney failure
- Damage to other organs
- High blood pressure
- Heart disease or heart attack
What are the tests for aHUS?
To check for aHUS, your doctor will do a complete blood count (CBC) test. A CBC test will measure your red blood cell and platelet count since having low counts can be a sign of aHUS.
You will also need a blood test to check how well your kidneys are working. Kidney health can be measured by a test called eGFR. eGFR is calculated using your creatinine level, as well as age, sex, and race.
The signs of aHUS can look similar to another condition called thrombotic thrombocytopenia purpura (TTP). For a doctor to decide whether you have aHUS or TTP, you will need to have a blood test that measures the level of a protein called ADAMTS13 in your blood. Low levels of this protein can show you have TTP instead of aHUS. Knowing whether you have aHUS versus TTP is important since the two diseases have different treatments.
What is the treatment for aHUS?
aHUS is commonly treated with a drug called eculizumab. For now, it is the only medicine approved in the United States to treat aHUS. Eculizumab can improve platelet and red blood cell counts. It may also reverse acute kidney injury and prevent kidney failure if it is taken soon enough. Eculizumab is given by injection at a doctor’s office.
Plasma therapies including infusions and exchanges are sometimes used to treat aHUS, but these methods do not treat the underlying disease. Plasma therapies work for treating aHUS in some people, but do not work for everyone.
How can I prevent aHUS?
Since aHUS is a disease related to a genetic mutation, there is no known way to prevent it. Although preventing aHUS is not possible, effective treatments are available. The best way to prevent aHUS from causing permanent damage in your body is early diagnosis and treatment.
Living with aHUS
Each case of aHUS is different. This can make finding the right care difficult. When you have aHUS, you should work with a nephrologist (a kidney doctor), and/or a hematologist (a blood doctor) to monitor your condition. You will need to have regular blood tests to check the health of your kidneys and your platelet and red blood cell counts.
Visit the aHUS Foundation for more information on living well with the disease. Read more about the blood tests recommended for aHUS. Download this tracker to keep track of your own values.
Where can I get more information?
- National Organization for Rare Diseases (NORD)
- aHUS Foundation
- National Institutes of Health (NIH)