Thread by @hedonish

I have a ton of brain fog today, so bear with me, but I saw a lot of convos happening about #MCAS last night and I wanted to chime in with some info I've learned in the last decade since my #mastocytosis diagnosis.

For those unfamiliar, everyone's bodies have #MastCells. They're part of your immune system and they're responsible for a few things, but primarily they store ~200+ chemicals (called mediators) and release them when fighting off infections, allergens, etc.

These mediators do lots of different things, and some of them are responsible for telling other cells in your body what to do. When Mast cells release mediators it can set off big chain reactions that can impact most, if not all, the systems in your body.

Many mediators are also able to cross the blood-brain barrier, which means they can impact inflammation and functioning of the brain. ncbi.nlm.nih.gov/pmc/articles/P… (I'll come back to this)

#MCAS and #Mastocytosis are what happens when mast cells don't behave the way they're supposed to. #MCAS patients have the correct amount of mast cells but they don't behave right. #mastocytosis have too many mast cells, they're spindle-shaped, and they're badly behaved.

Both are considered "Mast Cell Diseases." There's also different types of #MCAS (i.e. MMAS rarediseases.info.nih.gov/diseases/12980…) and several types of #mastocytosis, but I'll save that for another thread.

Despite the differences between diseases, the majority of the symptoms overlap between them, and the symptoms vary wildly between individuals. I've met fellow #mastocytosis patients whose main symptoms are nothing like mine and #MCAS patients who have the exact same symptoms.

Our badly behaved, overreactive mast cells tend to react to a laundry list of things (called triggers), which cause us allergic reactions that can present in a laundry list of ways (ranging from stomachaches, to brain fog, to flushing or a billion other ways).

Every patient has different triggers, although there can be a lot of overlap & new triggers can develop at any time (fun, huh?)

It's important to remember that us we can have the same disease(s), and still have completely different triggers, reactions, and symptoms. I've seen a lot of people lash out at each other over the last 10 years about differences in how their disease presents or is treated.

I'll tell people that #MastCellDiseases are the weirdest diseases they've never heard of, and they are. They're almost completely unpredictable, and that causes an intense amount of stress for most people who have them.

I could do the same thing every day and sometimes I'll have a reaction, sometimes not, with the severity of my reaction being different each time.

Here's how I explain it: Picture a cup & every trigger you encounter fills it up—some more than others. Are you stressed, tired, hot, have a reaction recently, etc.?

A million factors likely contribute to how full your cup is, and eventually, it overflows, causing a reaction.

This is my favorite illustration showing some of the potential spectrum of symptoms that mast cell mediators can cause.

This graphic is from an article published by Dr. Theo Theoharides. He also has lots of his other work available to read at mastcellmaster.com Disorders" by Dr. Theoharides showing mast cell activators and the wide range of symptoms that can result." src="/images/1px.png" data-src="https://pbs.twimg.com/media/Du4aIACW4AEGuki.jpg">

While folks generally use the term "allergic reaction" to refer to the reactions caused by both, there is a difference between "allergies" (which are usually IgE-mediated) and "sensitivities" (non-IgE-mediated). Sensitivities generally cannot be tested for using allergy testing.

This is why many of us will have allergic reactions to things that either don't show up on allergy tests.

That said, I know at least 1 person who has sensitivities that sometimes register as IgE-mediated allergies on tests and sometimes don't. Mast cell diseases are weird AF.

This is getting long, so I'll wrap it up:
Mast cell patients, you're going to have a lot more questions than answers, but research has come a long way in the last 10 years—in fact, #MCAS wasn't even a disease doctors were aware then. I'm hopeful more answers are coming.

Also, I just found that the link to the article by Dr. Theo I referenced earlier in the thread is now available publicly: mastcellmaster.com/documents/2018…

This is my go-to article to show new doctors unfamiliar with mast cell diseases. It does a great job covering the basics!