Mast Cell Activation Disorder and Endometriosis

Two illnesses that don’t play well together are endometriosis and mast cell activation syndrome (MCAS). Mast cells live in our bone marrow and tissues, and they are part of our immune response.

In people with mast cell disorders, these cells essentially attack everything, causing an allergy-like response. Typically, those with MCAS have a different combination of symptoms: some have gastrointestinal reactions, chronic pain, inflammation, flushing, hives, trouble breathing, or a runny nose, and some even have frequent anaphylaxis.

These disorders are multi-system and not well studied. You can read more about mast cell disorders here.

What causes MCAS to intensify?

Hormones are included on the long list of things that cause mast cells to overreact in mast cell patients. Therefore, the hormonal shifts that endo warriors experience throughout the month are even more of a minefield.

I suspect that one of the things that agitate my mast cells is estrogen. Since endometriosis creates its own estrogen, this causes quite an upset in my body.

Although I’ve had four surgeries to remove endometriosis and no longer have my ovaries, endo continues to recur and I notice that my mast cell reactions intensify as the endometriosis recurs.

Research from 2020 shows that MCAS may affect up to 17% of the population1. Diagnostic criteria were only established in 2010, and it was only classified as a disease in 2016, so there aren’t many doctors who understand or even know about it yet.

Getting a MCAS diagnosis

Just like with endometriosis, patients face an uphill battle to get MCAS diagnosed and treated.

Some doctors, including those in my own team, suspect that there is a correlation between the two illnesses and some research shows that targeting mast cells may be one way to treat endometriosis2.

Recently, I connected with someone in Australia who also deals with this difficult combination of illnesses, and even though we live half a world apart, speaking with her helped me feel less alone.

SpoonieCat (who prefers to use her online alias rather than her real name) is a cisgender woman. Like me, she has a bevy of chronic illness acronyms: PCOS (polycystic ovarian syndrome), hEDS (hypermobile Ehlers Danlos Syndrome), TMD (temporomandibular disorder), and MCAS in addition to endometriosis. She also has migraines and fibromyalgia.

The first illness SpoonieCat got diagnosed with was PCOS. A couple of years later, her health took a downward turn.

“Everything kind of went haywire in 2013 with stuff going really badly wrong. I ended up with a period that lasted six weeks,” she said. “I saw a gynecologist who put me through a D&C (dilation and curettage). While the doctor was there, they did a biopsy to find out what was going on. They found pre-cancerous endo cells.”

She’s been cancer-free for three years, and she’s glad she listened to her body and made an appointment with a doctor. Because had she ignored her symptoms, she “possibly would have had stage four endometrial cancer. It was really aggressive.”

Currently, she is on the Mirena coil to keep cancer cells from coming back, and she anticipates being on that for life.

After that ordeal, things continued to worsen with her health. In 2016 she started falling down stairs and “getting random headaches like I’d been struck in the back of the head with a hammer.”

She received diagnoses for migraines and hEDS at that point. Then she got really sick in 2017, but it wasn’t until last year that she finally got diagnosed with MCAS by an immunologist in Brisbane.

The diagnosis was a relief.

“It’s validation. I don’t think people who are not chronically ill know how important validation is,” she said. “You feel like, ‘yes, I am right to pursue this, to question this.’”

When asked what advice she has for other endo warriors, SpoonieCat recommended that they keep going, investigating, and asking questions.

“Don’t let anyone turn you away,” she said.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The Endometriosis.net team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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