At this time last year I had never heard of mast cell activation syndrome (MCAS) and the first time that I heard the name I thought that it was a “made up” disease. Since then I have come to realize that it is a real diagnosis and I have learned a ton about it, including the following:
MCAS is a newly recognized disease of the innate immune system (our bodies’ first line of defense against bacteria, viruses, parasites, and other invaders).
Women make up the majority of patients with MCAS.
Symptoms are caused by having too much histamine in one's system and can affect almost any part of the body (see comprehensive list below).
MCAS is very common (there is pilot data showing that 17% of Germans are affected to some degree).
It is acquired during life; no one is born with MCAS and it is not yet known why it develops in certain people.
I am one of the unlucky people to have acquired MCAS during my journey through life. Although I really wish that I didn’t have it, I am sharing my story in hopes that I can help others.
Mast cells are innate immune cells that play a role in defending the body against bacteria, viruses, and parasites, but are best known for their participation in the allergic response. When mast cells degranulate, or burst open, histamine and other chemicals are released, leading to symptoms which we associate with allergies, including having a runny nose, wheezing, hives, etc. Most of us are familiar with the antihistamine drugs that are used to treat allergic symptoms, such as Claritin, Allergra, and Zrytec. Although these medications do not prevent mast cells from releasing histamine, they prevent symptoms by blocking histamine receptors.
In mast cell activation syndrome (also known as mast cell activation disorder, or MCAD), mast cells have excessive degranulation, release too much histamine, and adverse symptoms develop. Symptoms can vary from person to person and will often become worse in the same person with time. Some patients will experience only one or two symptoms from having too much histamine floating around, and other patients will experience many, many symptoms. Although urticaria (hives) is the classic symptom associated with mast cell degranulation, in many cases patients with MCAS do not have urticaria or any skin findings. I have never had hives and the only skin symptom that I get from MCAS is facial flushing from time to time.
According to the Mastocytosis Society Canada’s website, the most common symptoms of MCAS include the following:
Gastrointestinal symptoms, including nausea, vomiting, diarrhea, abdominal pain, bloating, and malabsorption* (sounds a lot like celiac and/or irritable bowel syndrome doesn’t it?)
Low blood pressure*
Itching, flushing*, hives
Episodes of fainting or dizziness
Cognitive impairment (brain fog)*
Rapid weight gain or loss
Chest pain and/or a racing heart*
Sensitivity to sunlight
* = symptoms that I have personally experienced as a result of MCAS. I saw several different subspecialists before we were able to piece all of these symptoms together.
Common triggers for mast cell degranulation in those of us with MCAS include the following:
pain medications such as NSAIDs and narcotics
foods and drinks that are high in histamine or are known to trigger histamine release
extreme temperatures, both hot and cold
strong scents including perfumes and chemicals
friction, pressure, or vibration on the skin
emotional and physical stress
At this point, my only known triggers for MCAS are high histamine foods and foods that are histamine-releasing, including fermented foods and foods/drinks that have added sulfites. Please see my previous post “Celiac Disease and Multiple Food Intolerances” from July 2013 for more details on food triggers and high histamine foods. Since beginning treatment for MCAS late last summer, the other food intolerances that I had attributed to my celiac disease have markedly improved. My sulfite allergy/intolerance also appears to have been as result of untreated MCAS.
The first case reports of MCAS were just published in the medical journals in 2007 or 2008, so in most cases, the only doctors who have learned about MCAS during medical school are the really young ones. Systemic mastocytosis (SM) is a well-known, very serious mast cell disease in which there are too many mast cells in the body that invade into other parts of the body, including the bone marrow. In MCAS patients the numbers of mast cells are normal (this is what differentiates it from SM) but the mast cells that are present are overly active and degranulate much more often than they should. SM and MCAS share a lot of the same symptoms but MCAS is on a milder scale.
According to Dr. Larry Afrin, MD, a professor at the University of South Carolina who is one of the world’s experts on MCAS, testing should consist of the following:
1. Complete blood cell count with manual differential, comprehensive metabolic panel, and a serum magnesium level (these are usually part of a doctor’s evaluation for a patient presenting with any type of chronic illness). Coagulation studies and serum immunoglobulin levels may need to be done depending on presenting symptoms.
2. Blood tests consisting of serum tryptase and plasma histamine levels. If the tryptase is greater than 20 ng/mL, then a patient must be evaluated for systemic mastocytosis. In MCAS the tryptase, although often elevated, is almost always less than 20 mg/dL.
3. Plasma prostaglandin D2 (PGD2) and heparin levels.
4. Chilled 24 hour urine sample for PGD2 and methylhistamine.
In many cases of MCAS the baseline tryptase and histamine levels can be normal, so it is important for a patient to have these labs done two times (both at baseline and when symptomatic). Both blood and urine levels of histamine and tryptase should rise after mast cells are triggered. Therefore, MCAS cannot be ruled out based on one set of normal labs. This differs from many other diseases that can be ruled out if an initial set of lab tests are normal. In my case I had abnormally high urine prostaglandin levels on two separate occasions and my tryptase and histamine levels rose when I was symptomatic (both were totally normal at baseline when I did not have any symptoms going on).
Treatment options for MCAS include H1 antihistamines (such as Claritin, Allegra, and Zrytec and their generic forms), H2 antihistamines (such as Pepcid and Zantac), and mast cell stabilizers such as ketotifen and cromolyn sodium. I initially had a difficult time finding an H1-blocking antihistamine that worked for me, as most contain cornstarch and other sulfited ingredients which are triggers for my mast cells to degranulate. But I have recently done very well taking a compounded sulfite-free form of generic Claritin twice a day. I have also done my best to follow a low-histamine diet, and I believe that this has made the biggest difference in my symptoms improving. Yasmina, the Low Histamine Chef, who also has MCAS, has been a wonderful resource for learning about the low-histamine diet and recipes. If I keep my overall histamine intake low, I find that I can indulge in an occasional glass of wine or enjoy a small serving of aged cheese without starting to wheeze like I used to in the past.
Interestingly enough, since starting on this MCAS journey I have met about a dozen or so other women who have both celiac disease and MCAS. Many of us have found that our MCAS/histamine symptoms seem to spiral out of control after getting accidentally "glutened." DAO, the enzyme in our bodies that breaks down histamine, is produced in our digestive systems, so it does make sense that the gut damage we experience from gluten may lead to a decrease in DAO (and hence, our bodies getting overwhelmed with histamine that cannot be broken down). My gut instinct (no pun intended) is that many of us with celiac disease and non celiac gluten sensitivity have MCAS going on to some degree. I guess that time will tell...In the meantime, if you are experiencing symptoms that seem puzzling, involve multiple systems of your body, and popped up out of the blue, I encourage you to look into MCAS as a possibility and discuss your symptoms with your doctor.
There are some great references on the internet for learning about mast cell activation syndrome and histamine intolerance, including the following:
1. Mastocytosis and Mast Cell Disorders from the Mastocytosis Society Canada's website (www.mastocytosis.ca). Accessed Jan. 3, 2014.
2. Presentation, Diagnosis, and Management of Mast Cell Activation Syndrome by Lawrence Afrin, MD, chapter 6 in the book Mast Cells edited by David B. Murray, 2013.
3. Histamine Intolerance on Allergy UK website (www.allergyuk.org). Accessed Jan. 3, 2014.
4. Mast cell activation syndrome: a newly recognized disorder with systemic clinical manifestations. Hamilton, M., Hornick, J., Akin, C., et al. J Allergy Clin Immunol. 2011. 128 (1): 147-152.
5. Mast Cell Activation Syndrome: A Review. Frieri, M., Patel, R., Celestin, J. Curr Allergy Asthma Rep. 2013. 13: 27-32.
6. Histamine Intolerance by Dr. Janice Joneja on webpage www.foodsmatter.com. Accessed Jan. 3, 2014.
7. Expanding spectrum of mast cell activation disorders: monoclonal and idiopathic mast cell activation syndromes. Picard, M., Giavina-Bianchi, P., Mezzano, V., et al. Clinical Therapeutics. 2013. 35(5): 548-562.
Dr. Afrin's chapter on MCAS for physicians (#2 above) is the most comprehensive document that I have come across regarding all that is known about MCAS.
Lastly, I would like to thank my friend Harriet for all of her advice and help on this journey. If it was not for her assistance, I would probably still be wheezing and flushing with chronic brain fog and irritable bowel syndrome despite being strictly gluten free.
Happy New Year and thank you for reading!