Can you imagine what would happen if our own defense system, the immune system, instead of protecting us from disease, started attacking our own bodies? That's one unfortunate, but somewhat rare, condition we're going to talk about today is aHUS, or Atypical Hemolytic Uremic Syndrome . This is when our blood vessels become damaged, small blood clots form, and blood flow to vital organs like the kidneys decreases. This condition is often caused by a genetic mutation .
Doctors usually diagnose you with aHUS when you have all three of these conditions together:
- Microangiopathic hemolytic anemia : This means that your red blood cells are destroyed too quickly, so your body is unable to make new cells to replace them.
- Thrombocytopenia : This is a decrease in the number of platelets, which help blood clot.
- Acute kidney injury : This is a type of kidney failure, but it can sometimes be reversed.
All three of these conditions can occur simultaneously, or they can be exacerbated by other illnesses.
What is the difference between regular HUS and this aHUS?
In the past, this condition called HUS (Hemolytic Uremic Syndrome) was divided into two main types.
- Typical HUS (diarrhea-associated HUS): This is often accompanied by diarrhea. It is caused by a type of bacteria called E. coli . Some people also call it STEC-HUS .
- The aHUS we are talking about today (Atypical HUS): This is not the type of diarrhea that is seen. Most of the time, about half of people who develop aHUS, it is caused by a genetic change, a genetic mutation . Doctors sometimes call this condition complement-mediated thrombotic microangiopathy (CM-TMA) .
What are the specific triggers for aHUS?
Simply put, not everyone who has a genetic mutation will develop aHUS. Often, it is triggered, or exacerbated, by other health conditions. Consider these things:
- Pregnancy period
- Cancer
- Various infections
- Certain medications, especially chemotherapy agents , immunosuppressive medications , blood thinners , oral contraceptives , and some anti-inflammatory medications .
What are the symptoms of aHUS?
Now let's look at what symptoms a person with aHUS shows. You may have several of these, or you may have symptoms that develop gradually.
- Feeling tired all the time (Fatigue)
- Pale skin (Pallor)
- Nausea or vomiting
- Decreased urine output
- Blood in the urine
- High blood pressure (Hypertension)
- Difficulty breathing (Dyspnea)
- Edema
- Confusion , loss of memory
- Fever
Most people don't have all of these symptoms at once. Sometimes they come on gradually, little by little. You may feel like you've been suffering from something for a while, but you can't figure out what it is. These neurological symptoms, that's the confusion I mentioned earlier, don't happen to everyone, it's a little less common.
What really causes aHUS?
The main cause of aHUS is a change in our DNA (genetic mutation) , or the formation of autoantibodies that attack our own cells against the 'complement proteins' in our immune system . These genetic changes can be inherited from our parents, or they can occur randomly. These genetic mutations affect the function of proteins called 'complement factors' .
Think of these 'complement factors' as little soldiers that help our immune cells. Like seasoning food, these proteins find harmful germs (like bacteria and viruses) and mark them so that other immune cells can 'eat' them. The most commonly affected in aHUS are complement factors H, I, 3, and B.
For example, the function of complement factor H is to protect healthy cells in our body and to keep other complement factors from being activated when they are not needed. Now imagine what happens if this complement factor H does not work properly (that is, if there is a mutation in the CFH gene) ? Our cells do not receive the protection they need. Then here are the things that happen:
- Our own immune cells mistakenly attack and damage the cells that line the inside of our blood vessels (endothelial cells) .
- Platelets gather around this damage and form a blood clot. This blocks the blood vessels.
- This reduces blood flow to our organs, causing them to become damaged and their function to decline. The kidneys are the most affected.
- These blood clots damage other blood cells that pass through them, causing a condition called hemolytic anemia .
How do you know if you have aHUS?
A doctor will usually diagnose aHUS based on your symptoms and the results of tests that check your blood counts and how your organs are working. They will also do tests to make sure you don't have other diseases that cause similar symptoms (such as the aforementioned STEC-HUS).
What tests are used to diagnose aHUS?
You may need to do tests like these:
- Blood tests: Complete Blood Count (CBC) , kidney function tests, etc.
- Genetic testing : This checks for genetic mutations.
- Stool tests : Check for infections like E. coli.
- Kidney biopsy : Taking a small piece of the kidney for examination.
- Imaging tests : such as ultrasound or CT scan .
How is aHUS treated?
The treatment for aHUS depends on the underlying cause and the severity of the condition. If you have a milder form of aHUS, your doctor may monitor you and provide supportive care , such as blood transfusions or high blood pressure medication, if needed.
However, if you have severe aHUS, you may need treatment like this:
- Therapeutic plasma exchange : In this, the plasma part of the blood is removed and new plasma is given.
- Rituximab or other medications used to treat autoimmune diseases.
- Dialysis : A method of cleaning the blood when the kidneys are not working properly.
- Kidney transplant : This is only done in very severe cases.
For those with the aforementioned 'complement' gene mutations , doctors often use a drug called eculizumab to treat aHUS. Eculizumab works by blocking certain complement proteins, stopping your immune system from damaging your own blood vessels.
Are there any side effects of the treatment?
When using Eculizumab , you may be slightly less protected from meningococcal and pneumococcal vaccines. Therefore, if possible, your doctor may advise you to get these vaccines before starting Eculizumab .
What does the future hold for someone with aHUS?
If this condition is diagnosed and treated early, conditions such as acute kidney injury caused by aHUS can be successfully managed. You may have periods of remission without symptoms. However, if something else triggers aHUS again, it can become life-threatening again.
In the past, about half, or 50%, of people with aHUS developed end-stage kidney disease (ESKD) , which meant their kidneys became completely dysfunctional.
But there is good news! New studies clearly show that the risk of ESKD has been significantly reduced in people with aHUS thanks to the treatment Eculizumab .
What is the risk of death from aHUS?
Severe cases of aHUS, such as kidney failure or damage to other organs, are really serious. In such severe cases, there is a risk of death of about 15%.
Can aHUS be prevented?
Because it is often caused by genetic changes, aHUS usually cannot be prevented. However, if you are at risk of developing severe disease, you may be able to avoid some of the things that trigger it .
How do I take care of myself?
If you have been diagnosed with aHUS, talk to your doctor about ways to avoid things that could make the condition worse. It's also important to know the symptoms of a severe case.
When should I see a doctor?
If you've been feeling lethargic or tired for a long time – as if you have a chronic illness that won't go away – talk to your doctor. Also, talk about any other symptoms you've had recently, such as a change in your toilet habits.
When should I go to an Emergency Treatment Unit (ETU) ?
If you have these severe symptoms, go to an emergency room immediately:
- Urine output is greatly reduced.
- Confusion or altered consciousness.
- Severe swelling.
- Severe difficulty breathing.
What questions should I ask the doctor?
It may be helpful to ask your doctor questions like these:
- How serious is my condition?
- What caused this to escalate?
- Can I prevent situations like this in the future?
- What symptoms should I look out for?
- When should I come see you again?
How common is this condition called aHUS?
aHUS is a very rare condition. It affects about one in five hundred thousand people. It is slightly more common in adults than in children.
Finally, things to remember
Finding out that you or your child has a genetic condition can be a life-changing experience. aHUS is a serious condition that can cause blood clots and damage organs. However, the recent development of a drug called eculizumab has significantly improved the survival rate of people with aHUS. If you have been diagnosed with aHUS, talk to your doctor about ways to avoid triggers and reduce your risk of serious illness. He or she can help you understand what you need to do to stay healthy.
` aHUS, kidney disease, blood clots, immune system, genetic mutations, anemia, Eculizumab
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