How to Tell If You Have Mast Cell Activation Syndrome

If you’ve been searching for solutions to your mysterious health symptoms, they could be caused by Mast Cell Activation Syndrome.

Mast cell activation syndrome (MCAS) is an immunological condition where mast cells inappropriately secrete mast cell mediators. Mediators include but are not limited to histamine, which can cause widespread and chronic inflammation.

This mediator release can be excessive and/or chronic and result in long-lasting symptoms in almost any cell of the body where their receptors are found. This can potentially affect every organ system in the body.

Some experts believe as many as 14 to 17 percent of the US population have MCAS, which is one out of every six to seven people. It’s also been estimated to take up to 10 years to reach a MCAS diagnosis. This is mostly due to the lack of awareness surrounding MCAS.

Because mast cell activation syndrome goes unnoticed for years, I’d like to dig a bit deeper and uncover some of the symptoms and lab work available that can help with MCAS diagnosis.

Symptoms of MCAS

Patients who have MCAS typically have been struggling with inflammation-related symptoms over the years, which commonly include:

  • Having allergies as a toddler
  • Various rashes that came and went
  • Gut conditions (that may have been misdiagnosed)
  • Anxiety
  • Headaches
  • Insomnia
  • Poor wound healing

While these are common MCAS symptoms due to mast cell mediators occurring throughout the body, a person can be affected by symptoms that are more widespread. These can include, but are not limited to:

  • Feeling as though you’ve always been sick
  • Overreaction to bee stings and mosquito bites
  • Shortness of breath
  • Feeling lightheaded when you stand
  • Insomnia
  • Ringing of the ears
  • Facial and chest flushing
  • Frequent colds, infections or fevers
  • Food, chemical, and drug sensitivities and intolerances
  • Heat intolerance

You can also find a comprehensive list of MCAS symptoms in my in-depth article, Mast Cell Activation Syndrome and Histamine: When Your Immune System Runs Rampant.

You have the option to get testing done with a doctor to help confirm the MCAS diagnosis. I recommend you have these tests done with a doctor who’s experienced in MCAS because it’s still largely unknown, even in the medical community.

Lab work for MCAS

Working with a doctor who specializes in MCAS is your best bet as you’ll need to get testing on multiple occasions since the symptoms of MCAS wax and wane. False negatives are a common occurrence with MCAS testing. In fact, positive lab work is only obtained 20 percent of the time. However, testing can still give you a lot of valuable information regarding your mast cell mediator status. Testing for MCAS is quite complex and requires specialized handling of tissue samples.

The most important tests are:

  • Histamine – plasma – Quest 36586 – must be chilled. Normal range – 28-51 ug/l.
  • N-Methylhistamine – 24-hour urine – must be chilled. Normal range – less than 200 mcg/g.
  • Prostaglandin D2 – plasma – must be immediately chilled and spun in a refrigerated centrifuge. Must be off NSAIDS (Motrin, Advil), aspirin, ASA, anything containing aspirin, for 5 days.
  • Prostaglandin D2 (PGD2) – 24-hour urine – specimen collection must be chilled. Must be off NSAIDS (Motrin, Advil), aspirin, ASA, anything containing aspirin, for 5 days.
  • Chromogranin A – Quest 16379 – must be off proton pump inhibitors (PPIs) and H2 blockers (Pepcid and Zantac) for 5 days before tests, since they can falsely elevate chromogranin A.

There are others you can have taken, which you can find in more detail in my in-depth article, Mast Cell Activation Syndrome and Histamine: When Your Immune System Runs Rampant.

More information regarding a low-histamine diet may found found in my guide here.


14 thoughts on “How to Tell If You Have Mast Cell Activation Syndrome”

  1. Really concerned. I cant stop itching especially at night. My rheumatologist is currently testing me for this.

    • Hope you find the answers you’re looking for. Have you managed to get confident results from your rheumatologist?

  2. I really appreciate this article and all the information in it. I’ll guide others to this page and share this with doctors, here in the United States. Unfortunately, most doctors are not open to learning. Got my diagnosis in 2012, had to fly three times to a great doctor, who understood MCAS and tested properly. Can’t say enough about trigger avoidance and the correct medications. Finding, only recently, there are some supplements that also help. Butterbur is one of my favorites, and you are the only one who has ever mentioned it!
    Thank you!

  3. I am seeing an immunologist on Friday, are there any questions I should ask, other than the tests outlined in this article? I might have MCAS, I have had urticaria nearly every day, with many triggers, since 1-2 weeks after suspected Covid. Do you think cases caused by a specific virus have a hope of being cured, or simply stopping spontaneously one day?

    • The tests outlined in my blog posts are the tests that need being done. They do however, require a refrigerated centrifuge to be accurate. As to prognosis, there are so many variables to consider that emerge after taking a thorough history and doing extensive testing, it is very hard to predict.

  4. Under the care of my Naturopath I started on a SIBO diet. It’s been a month and I started to go into the more mid range foods. Since bringing new foods back in my diet I’m reacting to just about everything I eat.
    My biggest symptom feels like my body is stuck in histamine mood. I’m itchy, brain fog bad, but the biggest symptom is my whole body vibrates constantly. I’ve tried taking a antihistamine and it didn’t help.
    Could this be a possible MCAS?

    • Thank you for reaching out. It certainly sounds as if you are experiencing many symptoms that may be mast cell activation syndrome. In order to determine if you have Mast Cell Activation Syndrome and what you can do about it, Dr. Hoffman would need to do an intake and health history along with specific functional medicine testing. We would be happy to book an appointment for you. The best way to book is to call the clinic at 403-206-2333. In order to understand how the clinic operates, be sure to read the FAQ banner at the top of the website and read Dr Hoffman’s many blogs on MCAS, including the recent article he co-authored with Dr Afrin. Thanks for the enquiry and I hope we can be of help.

  5. Unfortunately a trip to see Dr Hoffman is not possible for me. I live in NW FL close to AL state line and have been looking for someone who has knowledge of and treats MCAD. Im willing to drive 2hrs if needed to find help. Can you personally recommend someone in my neck of the woods? I enjoy your writings and find them helpful and I appreciate your help with this long search.

    • Unfortunately, we are not able to recommend anyone in your area. Dr. Hoffman does offer telemedicine consultations if this would be of interest to you.

  6. I’ve recently been diagnosed with Histamine Intolerance and I’ve been reading information on it. This is how I came upon your website. I am suspecting I have MCAS. I have been very unwell this past week: migraine, headache for 5 days, small bumps all over my scalp, pain, dizziness, some flushing episodes and I vomited twice for no apparent reason. I am waiting for a call back from the dermatologist that I have begun to see. I’m not sure if you can advise me but what tests would be beneficial? I also read that Dr. Hoffman does telemedicine. Is there a fee for this?
    Any help would be muchly appreciated!

    • Dr. Hoffman does offer telemedicine appointments, please reach out to the clinic at 403-206-2333 to reach our patient support assistants that can answer your questions.


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