Welcome to my disease. What is atypical Hemolytic Uremic Syndrome (aHUS) or Complement-Mediated Thrombotic Microangiopathy (CM-TMA)?

A basic explainer of the complicated rare disease that triggered all my trouble and almost murdered me.

Hi, If you’re new here, I started writing a book six months ago when I was on dialysis. It’s intended to be both memoir and a practical tool to help folks who might be going through something similar or those caregivers and family supporting someone with a challenging diagnosis. I hope to include excerpts here as I write. NOTE: This is not intended to replace actual medical guidance. Please consult your doctors on your individual challenges and situations. Also names have been changed for most of my medical staff.

What is aHUS or CM-TMA?

This disease is confusing. It’s all alphabet soup. I recall any explanation washed over me for months.

But now, after a year, I’ve figured out how to explain it.

So for starters, we’ve got an immune system. It helps protect us from bacteria and viruses.

Inside that system, there is something known as the complement cascade.

My Football Metaphor

The complement cascade is a brute squad. It’s a crew of proteins and cell receptors. They roll together and are particularly good at attacking bacteria.

I liken them to a football offensive line. But also alongside them are referees. This offensive line is aggressive and the referees keep them on the field. 

But in my body something is wrong with the referees and the offensive line is overactive, beating up the coach, the fans in the stadium, and the people who sell peanuts.

Tiny Blood Clots

The system beats up my own cells so much it causes something called thrombotic microangiopathy or TMA - aka tiny blood clots. This is the hallmark of the disease.

The tiny blood clots like to target small blood vessels in particular. Kidneys are full of small blood vessels so it becomes a hot spot for the TMA, often cutting off blood flow and causing organ failure there. This is the “uremic” portion of the disease. Because the kidneys are hit hard, kidney damage is an ongoing challenge for folks with this disease.

The tiny clots also can migrate and clump together causing larger blockages.

TMA often shows up in other places besides the kidney as well. For me, I had clots in my pelvis and in my lungs and heart and my baby’s cord.

How do you get it?

The disease is caused often by a genetic mutation, but many folks like myself don’t have a known genetic marker. So science doesn’t know yet for folks like me.

It often needs a stress event in the body, like a virus or pregnancy, to trigger the complement cascade into action in such a way that it goes out of control.

How do you stop it?

To stop the cascade, patients usually take a complement-inhibitor drug that does the work of the regulators to keep the system at bay. It does make patients very susceptible to infection, especially meningitis. So patients have to be very careful because they are immunocompromised.

There is no cure for aHUS or CM-TMA. Folks remain on the infusion drug throughout their lives (or until a new drug comes along). Some patients have periods of remission and some lucky patients even go off medication and have no repeated flares.

Why are there two names?

Atypical Hemolytic Uremic Syndrome or aHUS is a bad name frankly. Typical HUS is a disease itself with separate cause (usually gastrointestinal infection) and prognosis, while atypical is a nebulous version of the name that doesn’t fully explain what’s happening. 

It’s a name so bad, it doesn’t help doctors and can often lead to long diagnosis times.

Complement-mediated Thrombotic Microangiopathy or CM-TMA is an accurate labeling of the problem and cause; tiny blood clots caused by the complement system. This name has not been widely adopted however because it’s fairly new. Even many patients haven’t heard of it as well as insurance companies. 

What are the symptoms?

Symptoms of the disease are super vague: fatigue, nausea, vomiting, irritability. (You know, none of these flag when you’re also a pregnant person). 

Unfortunately, by the time most patients get care, their kidneys are being very impacted. A key flag of this disease differentiating it from kidney shock would be low platelets and signs of cell destruction. 

The disease is aggressive. Patients need treatment quickly, usually before a biopsy and an official diagnosis. A hematologist and nephrologist should work together to organize care and treatment.

How rare is it?

Honestly, we don’t know how many people have it. The medical system is poor at diagnosing, so many folks likely die before treatment. According to the National Institute of Health, “aHUS is a rare subtype of TMA caused by dysregulation of the complement pathway with an incidence of 0.23-0.43 cases per million population.” 

Okay, gimme the scary info:

Nope. Sorry, but I’m not going to discuss mortality rates because with quick treatment, results are quite optimistic. Don’t go down that road. Keep it positive. Unless you’re a doctor, then google away!

Tell your doctors and spread the word

It’s important for doctors to be aware of this disease, so please share this. My doctors had two suggestions for other doctors:

1. My nephrologist suggests always thinking about aHUS because otherwise you’ll never think about it.

2. My hematologist says doctors should always check their messages on the weekend. This disease won’t wait til Monday. Treatment is needed quickly.

Thankfully for me, he read that message on a Saturday.

Here’s a video of me doing a Q&A if you want to learn more: TIKTOK on aHUS or CM-TMA

If you have more questions feel free to drop them in the comments!

If you’re new here and wondering, “what happened to this lady?” my story starts here The Fighter Still Remains Part 1. xo

Thank you to Richard Burwick, MD for your founding level donation! You not only supported the team saving my life, you’re amazingly supportive of my writing.