Mast Cell Activation Syndrome (MCAS)

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MCAS and endometriosis

MCAS and histamine intolerance (HI) are separate co-conditions from endometriosis and not everyone with endometriosis has these conditions. However, I’ve come across many people who have endometriosis and HI or MCAS. Mast cells do play a role in endometriosis but I don’t have enough knowledge on the topic to comment on it.

Mast cell activation syndrome is when mast cells, which are involved in the body’s allergy response, are overactive and release inflammatory molecules at inappropriate times

“Mast cells are a type of blood cell which are found in all body tissues. These cells play a key role in the immune system. In the event of an injury or an infection, mast cells become active and release chemicals called mediators. In a healthy state, mast cell mediators create a number of protective responses in the body to help fight infection and promote healing. In someone with MCAS, where these mediators are released too frequently, they can affect the body in multiple ways – causing multiple symptoms in different parts of the body at the same time.” [Source: Mast Cell Action]

Mast cells release hundreds of mediators, including histamine. 

MCAS triggers can include:

• food/drinks
• supplements
• fragrances
• cleaning products
• personal hygiene products/skin care (makeup, soap, hair dye, etc)
• temperature
• stress
• excitement
• exercise
• vibration
• sex
• exercise
• medicines 
• and more

Symptoms can include:

• headache, brain fog, anxiety/panicky feeling, insomnia, tinnitus, vertigo
• hives, flushing, swelling, itching
• dry throat, hoarseness in voice, sneezing, runny nose, watering eyes, post nasal drip
• diarrhea, constipation, bloating, abdominal pain
• racing heart, lightheadedness, woozy feeling
• fatigue, urinary symptoms, muscle pain
• anaphylaxis
• and more!

You don’t need to have all of those symptoms.

Most of my symptoms have been neurological or related to dysautonomia. Here’s some of the worst symptoms I had:

• intense insomnia for over a year. After 1-2 nights with no sleep, I would pass out for 5 hours then start the cycle of no sleep over again.
• vulvar burning because I became allergic to my own pee.
• post nasal drip and waking up multiple times a night like I’m choking.
• vertigo and dizziness.
• allergy symptoms like sneezing 30 times an hour and nose running for hours.
• panic/anxiety feeling.

Histamine intolerance (HI) and MCAS are not the same thing

A person can have one or both of these. Many of their symptoms overlap, but MCAS symptoms may (but not always) be more severe, have a very quick onset after the trigger exposure, be in multiple body systems, include anaphylaxis, have a broader range of triggers than HI (especially beyond just high histamine foods), and/or more. Here’s a helpful article if you’re trying to differentiate which one you may have.

I have some information on Histamine intolerance here.

Getting diagnosed

There are different schools of thought for diagnosis.

Vienna Consensus – high tryptase

“The definition of MCAS after the Vienna consensus is based on three diagnostic criteria that have to be fulfilled before the diagnosis of MCAS can be established:

1. typical (MCA-related) clinical symptoms;
2. an event-related increase in serum tryptase above the individual’s baseline tryptase (sBT)…
3. and response to drugs directed against MCA or the production or effects of MC mediators.”

[(1) Source: Selecting the Right Criteria and Proper Classification to Diagnose Mast Cell Activation Syndromes: A Critical Review]

However, a group of MCAS practitioners have come up with broader criteria for MCAS 

1. more symptoms are included (and the patient doesn’t need to have anaphylaxis)
2. broader range of elevated mediators: tryptase, histamine, prostaglandin D2, heparin, chromogranin A, etc (the patient doesn’t have to have elevated tryptase)
3. needing a response to MC stabilizers or H1/H2 histamine blockers, etc [Diagnosis of mast cell activation syndrome: a global “consensus-2]

In my own case, I don’t meet the criteria for the Vienna consensus because my typtase is normal. However, I have elevated chromogranin A, which doubled in levels from baseline when I was flaring. My previous doctor follows the Vienna consensus and told me while I don’t meet the stricter criteria for MCAS (even though I meet the broader criteria), that I definitely have “dysautonomia with a mast cell component”. However, there’s many people in the MCAS community like myself with normal typtase, which has led to a push against the Vienna consensus by both patients and some doctors due to the stricter criteria.

In spite of my doctor not giving me an official MCAS diagnosis, I have no doubt that is what I have after educating myself on the conditions and watching my symptoms, triggers, and improvements using typical MCAS medications and supplemements for over 5 years. Because my symptoms quack like MCAS, my doctor still treats my case that same way he treats his MCAS patients.

It’s important to rule out any other conditions that could be causing symptoms

These could be things like:

• neurological conditions like multiple sclerosis or dysautonomia
• endocrine issues like thyroid disease
• hormonal like low estrogen, low progesterone, or low testosterone; perimenopause, menopause
• mental health conditions like anxiety or depression
• digestive like inflammatory bowel disease, gut infections
• skin issues like rosacea, contact dermatitis
• and more

“…A number of conditions and disorders can mimic symptoms of MCA or MCAS. These conditions have to be considered in each case, especially when MCAS criteria are not fulfilled.” [(2) Source: Doctor, I Think I Am Suffering from MCAS: Differential Diagnosis and Separating Facts from Fiction]

Finding a doctor

It’s important to see an allergist who is knowledgeable in MCAS if you suspect you have it. The first allergist I saw ran an allergy panel, said I wasn’t allergic to anything, and sent me on my way! He also wasn’t able to recognize my chin swelling as an allergic reaction and sent me to a dermatologist, who told me that it was the sign of an allergic reaction.

Additionally, since many times people have symptoms in different body systems, they may see a cardiologist for their racing heart, a dermatologist for their skin rashes, a psychologist for their anxiety, etc. It can take time to realize that your symptoms are seemingly connected and possibly from HI or MCAS.

Functional medicine

I have found functional medicine doctors and naturopaths to be very helpful in helping me manage MCAS. Just like any doctor, it’s important to see functional medicine doctors and naturopaths who are knowledgable and to know what red flags to look for. It would be best if they specialize in MCAS and/or HI. In my own case, using supplements in addition to lifestyle changes helped me better stabilize my mast cells, and I couldn’t have done it without the help of a naturopath who really knew how to guide me. 

Managing MCAS

See my page Managing MCAS.