Differentiating Mast Cell Activation Syndrome (MCAS) From POTS

Cort

Founder of Health Rising and Phoenix Rising
Staff member
From Dysautonomia International

.....................

On MCAS

So what tests can be done to determine if the mast cells are misbehaving? The first test that is usually done is a blood test for tryptase. Tryptase is a protein that comes from mast cells and it is usually elevated in two circumstances. The first is after a severe allergic reaction (anaphylaxis) and the second is if you have too many mast cells in your body (mastocytosis). If you have a significantly elevated tryptase, your doctor might recommend a bone marrow biopsy which is usually the definitive test for mastocytosis. Mastocytosis can be a serious illness, but it is different than the problem that most people with MCAS have. In mastocytosis, there are too many mast cells due to a genetic mutation that made one cell start to grow and divide without control. Patients with mastocytosis and MCAS are treated differently.

For most people with POTS, the tryptase level is normal and they don’t have mastocytosis. In these patients we need to look for other clues that their mast cells are not functioning normally. There are many different chemicals that come out of mast cells and can be measured. Substances like histamine, prostaglandins and leukotrienes are usually measured in a 24 hour urine sample. If the symptoms fit and the patient has evidence of making too much of a mast cell chemical, many physicians are then willing to diagnose MCAS and move on to treatment.

Although different diagnostic criteria are published, a commonly used strategy to diagnose patients is to use all three of the following:
  1. Symptoms consistent with chronic/recurrent mast cell release
    a. Recurrent abdominal pain, diarrhea, flushing, itching, nasal congestion, coughing, chest tightness, wheezing, lightheadedness (usually a combination of some of these symptoms is present)
  2. Laboratory evidence of mast cell mediator (N-methyl histamine, prostaglandin D2 or 11-beta- prostaglandin F2 alpha, leukotriene E4 and others)
  3. Improvement in symptoms with the use of medications that block or treat elevations in these mediators
A word of caution about laboratory testing… many of the labs that can be ordered need to be sent on ice. If the labs are drawn at a facility that does not understand what is necessary, the samples may come back falsely normal. Testing is ideally going to be abnormal immediately after a flare up of symptoms. It would make sense to wait for testing on a “bad day.” There are several labs that can be ordered to help identify mast cell activation, but none of them are 100% accurateand all should be interpreted with care.

 
I just wanted to mention that it is common for many of us to believe we have MCAS, yet all laboratory work is normal. Instead, many physicians are diagnosing "presumed MCAS" or "MCAS - mediator negative" (or they throw up their hands and say "MCAS"). Patients have the symptoms and most are responding to antihistamines, so it must be mast cell activation, right? Not necessarily.

If we have these symptoms and respond to antihistamines (as I did), it means we have a condition that is related to histamine. By ignoring other histamine-producing cells (and by assuming that MCAS is the cause of POTS and the main cause of fatigue), we may be missing too much.

Mast cells are also attracted to inflammation. If we assume mast cells are the problem, we risk missing the underlying problem causing the mast cells to be activated (if that is indeed happening). That leaves us chasing our tails -- trying more and more aggressive forms of mast cell treatment, instead of trying to locate the source of inflammation.

I used to believe that mast cells were basically "everything"! Reading the signs and symptoms, it certainly seemed like it. But this narrow focus may be detrimental for us in the long-run.
We can't afford to stop thinking prematurely!

:D
 

Cort

Founder of Health Rising and Phoenix Rising
Staff member
I just wanted to mention that it is common for many of us to believe we have MCAS, yet all laboratory work is normal. Instead, many physicians are diagnosing "presumed MCAS" or "MCAS - mediator negative" (or they throw up their hands and say "MCAS"). Patients have the symptoms and most are responding to antihistamines, so it must be mast cell activation, right? Not necessarily.

If we have these symptoms and respond to antihistamines (as I did), it means we have a condition that is related to histamine. By ignoring other histamine-producing cells (and by assuming that MCAS is the cause of POTS and the main cause of fatigue), we may be missing too much.

Mast cells are also attracted to inflammation. If we assume mast cells are the problem, we risk missing the underlying problem causing the mast cells to be activated (if that is indeed happening). That leaves us chasing our tails -- trying more and more aggressive forms of mast cell treatment, instead of trying to locate the source of inflammation.

I used to believe that mast cells were basically "everything"! Reading the signs and symptoms, it certainly seemed like it. But this narrow focus may be detrimental for us in the long-run.
We can't afford to stop thinking prematurely!

:D
Interesting...Nice point about mast cells being involved generally in inflammation. As Younger says the idea right now is reduce inflammation.
 

Snookum96

Active Member
I just started reading about mast cell stuff in the last few days. Thanks for posting this Cort there is so much to learn about different illnesses with similar symptoms I am finding it all a little overwhelming! I see it was posted in May but I haven't had a chance to get through everything yet.
 
Interesting...Nice point about mast cells being involved generally in inflammation. As Younger says the idea right now is reduce inflammation.
Thank you, Cort. Yes, I think many of us patients sort of figured out on our own that we were inflamed (often despite normal markers of SED rate, CRP -- some typical inflammatory markers). Mast cells can magnify inflammation, cause inflammation, or just get caught up in the inflammatory cascade -- and the difference is crucial. The trick is trying to figure out the source of the inflammation, and how to best hit it.
I have no doubt we'll get it eventually!
 

JoseButts

New Member
It has been seen that patients having POTS (postural orthostatic tachycardia syndrome) also have MCAS (mast cell activation syndrome). Mast cells are large tissue cells that are present all through the body, having highest amounts in the skin, and the bone marrow. They consist of granules, which accumulates lots of chemicals along with tryptase and histamine. When mast cells are activated inappropriately, the released chemicals can cause various diseases. The first pathology test usually done in this case is a blood test for tryptase. Test usually performs after a flare up of symptoms.
 

Issie

Well-Known Member
Some of us with POTS have MCAS along with it. And for this subset type many of us have EDS (Ehlers Danlos). We call it the trilogy.

I agree that inflammation is a biggie here. Also faulty autoimmune responses.
Sometimes overactive and yet at the same time underactive.

Here is a site of a girl that has MCAS very bad. She is always trying to educate and help others.
http://www.iamast.com

Issie
 

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