Skip to content →

What is MCAS?

Mast Cell Activation Syndrome (MCAS)

MCAS is also commonly referred to as Mast Cell Activation Disorder (MCAD)

Let’s start with “what’s a mast cell?”

Mast Cells
Human Mast Cells (looking like blueberries.)

Unless you’re a medical professional you’ve probably never heard of them. I certainly hadn’t. Mast cells are best known for being a key player in serious allergic reactions… like someone having anaphylaxis from bee stings or peanuts, or an asthma attack triggered by something like smoke.

These cells are part of the immune system and play a vital role in chemical transmission throughout the body, though the details are still poorly understood. These little cells are activated and actually explode (fancier term- degranulate) to release a huge variety of chemicals, presumably depending on what activated them. These chemicals are used to mediate other reactions like digestion and many other things yet to be discovered; this is why you’ll often hear these released chemicals referred to as mediators. One thing they do seem to know- mast cells promote inflammation and cell proliferation for wound healing.

Mast cells are born from stem cells in the bone barrow. They’re prolific, being found in most tissues throughout the body, but the greatest numbers are found in the gastrointestinal tract and skin. They’re even found in close contact with neurons, but the exact purpose is still a mystery under research.

What is MCAS?

This is what happens when mast cells aren’t working properly. For some reason (not yet known) these cells are releasing chemicals when they shouldn’t, resulting in a list of unpleasant symptoms. It’s speculated that maybe mast cells are altered genetically, maybe as a part of a connective tissue problem, or perhaps that MCAS is even autoimmune in nature. The fact is we don’t know yet, but researchers are working on it. Also important to know is that MCAS is NOT the same as mastocytosis. MCAS is essentially having a normal amount of mast cells that aren’t working correctly, whereas mastocytosis is a problem of too many mast cells thanks to a cell proliferating out of control (akin to cancer).

Watch mast cells degranulate…

Symptoms

I can’t do this justice, but these are common symptoms I often hear about in addition to my own. Yes, there is a lot of overlap with POTS symptoms. For a very thorough description Page 50 of: Presentation, Diagnosis, and Management of Mast Cell Activation Syndrome by Dr. Lawrence Afrin.

Mental: Anxiety, Brain fog- difficulty concentrating & recalling words/facts/memories, Depression, Mood swings, Panic attacks, Irritability

Gastrointestinal: Abdominal Pain, Constipation, Cramping, Diarrhea, Nausea

Dermatological: Chronically dry skin, Flushing, Foliculitis, Hives, Itching, Pale skin, Rashes, Dermatographia (skin writing- raised warm red welts from scratches)

Respiratory: Chronic congestion, Coughing, Nasal stuffiness, Wheezing, Difficulty breathing deeply

Cardiovascular: Heart palpitations, Dizziness, Fainting, Near-fainting, Lightheadedness, Low blood pressure, High blood pressure

Vision: Blurred vision, Dry irritated eyes, Red eyes

Auditory: Sound sensitivity, Tinnitus

Pain: Headaches, Migraines, Joint pain, Chest pain, (Abdominal pain)

Other: Weight gain and retention despite low calorie intake and exercise, Slow time to heal wounds

Anaphylaxis If too many mediators are spilt into your system, you may also experience anaphylaxis, which primarily includes: difficulty breathing, itchy hives, flushing or pale skin, feeling of warmth, weak and rapid pulse, nausea, vomiting, diarrhea, dizziness and fainting.

Anecdotally, those who react immediately after exposure to a trigger are called “shockers,” and those that react later are called “leakers.”

Common triggers

These common triggers are things that can cause symptoms, or just make those symptoms so much worse.

    • Specific foods (specific to patient)
    • Emotional and physical stress
    • Exercise
    • Hot or cold temperatures
    • NSAIDS (non-steroidal anti-inflammatory drugs), antibiotics, and other medications
    • Skin friction or pressure
    • Strong scents or smells (even from innocent perfumes)
    • Bug bites


What’s it really like to have MCAS?

  • New fears. Things that you used to take for granted now become a source of fear. Exerting yourself too much, eating the wrong food, getting too emotional, or getting too warm can all end up sending you to the ER.
  • Limited exertion. You can actually be allergic to exercise. A few hours after a strenuous workout I have a delayed allergic response called anaphylaxis (this makes me a “leaker”). Yes, it’s weird. My heart rate goes through the roof. I feel like I’m dying. I get uncontrollable shake/shivers, vomiting, nausea and go ghost white. All just from a session at the gym. Other people with MCAS get their symptoms during or right after exercise. They can get hives, dizziness and have trouble breathing along with other awful symptoms.
  • Limited diet. Many with MCAS will react to certain foods, and the list can become long. Even simple ingredients like sugar or MSG from your favorite Chinese food can trigger symptoms. I can’t drink any alcohol anymore, because I’ll get the worst of possible symptoms- anaphylaxis (as I describe in my first post).
  • At the mercy of the air. A whiff of someone’s perfume or cologne can be a trigger. This can make going out into the world difficult, because you can’t control the air. The best you can do is wear something like a Vogmask. Forget going to the local home store with the heavy odors of fertilizer and paints. As a healthy person I hardly registered smells, and a waft from someone drenched in cologne was a mere annoyance, but for someone with MCAS this can ruin their entire day. Imagine turning the dial up on the list of symptoms above from just breathing some fragrant air.
  • No warm weather. Hot or cold temperatures are a common trigger for MCAS. That makes going outside difficult! “Hot temperatures” for me above 75℉. Not exactly a lot of wiggle room. After standing in warm weather a few minutes I find it incredibly difficult to stand, my heart rate will shoot up and I’ll have to sit or lay down or else I’ll pass out. That’s accompanied by nausea. It’s like getting hit in the gut with the flu just from trying to be in beautiful beach weather… and I love the beach.
  • Leaving the house requires bravery. The price to pay for exposure is to triggers is high, because you can end up feeling very bad for hours or days. Amazing all people with MCAS don’t just become agoraphobic hermits. After your symptoms have been triggered, you can’t just stop the “trigger” and feel ok. You can’t stop exercising, or get away from fumes and immediately rebound. This is because the mast cells have dumped their chemicals into your system and it takes time to process and eliminate them. Even after acute symptoms like swelling or nausea subside, good chance you’ll be exhausted and fatigued for days as your body recovers from the toxic dump of your mast cells.
  • You’re less reliable. Some days may be drastically better or worse than others, often times for no knowable reason. This makes planning social and professional engagements a huge challenge, if not impossible. Can you make that presentation? Can you even make it to the movies or that coffee joint? Having an unreliable body changes and strains almost all your social relationships. Your true friends and family will adjust and help, and others will fall away from your life. You experience loss, anger, and maybe even shame.
  • Anxiety for attacks. Going anywhere can cause anxiety, especially given all the potential triggers that can cause a life shaking event. You probably battle a justified and logical anxiety, and constantly plan the worst case. Trying to be safe is a struggle. Do I have all my emergency meds? Where’s the closest ER/Urgent Care? Where are the bathrooms? Will I be safe if I need to lay down or use an epipen? These are not the questions of a hypochondriac. Knowing these things makes you safer. Attacks happen and can’t be reliably prevented at all times. They come on quickly, with little to no time to get out of a store or social situation. The best you can do is reduce your exposure to triggers, while balancing the need to live life.
  • …Then having an attack. You experience attacks that are scary and incredibly socially awkward. An attack doesn’t have to be full blown anaphylaxis. You can have a cluster of intense awful symptoms that disable you. We all have them. The unpredictability of them amplifies their awfulness. My scary attacks involve my heart rate shooting up, which comes with a sense of doom in itself. Then, feeling a wave of dizziness, I start shaking, shivering and chattering uncontrollably. I know this means to lay down ASAP or my body will pass out and do it for me. If the attack escalates, I often feel the overwhelming need to empty my bladder, then my bowels. How am I supposed to use the toilet when I can’t even stand? I take emergency meds, sometimes I can get there myself, sometimes I get carried, and at my absolute worst- bedpans like a 90-year-old (in private thank sweet baby goodness). I feel like I’m dying, though I never do.
  • Losing or downgrading your career. Working a full-time job can be hard, if not impossible. You may have to reduce your work schedule and lose career advancement, if not let go of your career entirely. And if you’re able to keep your career, you’ll probably be working MUCH harder than those healthy counterparts around you. I had to leave my full-time job as a professional mechanical engineer, creating a huge loss of financial independence and identity. Healthy people having a taste of this condition would call in for a sick day and get to the hospital.

 


A fantastic review of MCAS and how to test for it, by Dr. Andrew White of Scripps:

http://www.dysautonomiainternational.org/blog/wordpress/a-tale-of-two-syndromes-pots-and-mcas/

More References:

Mast Cell Activation Syndrome- A Review: http://www.ncbi.nlm.nih.gov/pubmed/23179866

Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3069946/

Presentation, Diagnosis, and Management of Mast Cell Activation Syndrome by Dr. Lawrence Afrin: https://www.novapublishers.com/catalog/product_info.php?products_id=42603

Mayo Clinic- Anaphylaxis: http://www.mayoclinic.org/diseases-conditions/anaphylaxis/basics/symptoms/con-20014324