What are mast cell disorders?

Everyone has mast cells throughout their body. When a person comes into contact with a chemical or substance to which they may react, their mast cells are activated. They degranulate and give off histamine and other chemicals, called mediators. The histamine and other chemicals pumped into their system by the degranulating mast cells cause the person to exhibit the symptoms we typically associate with an allergic reaction—sneezing, watery eyes, rashes, hives, itching, tongue swelling, difficulty breathing, runny nose, skin flushing, and more.

Mast cell disease(s) (MCD) is the term used by mast cell specialists in the U.S. and internationally for all mast cell diseases and it includes every person suffering from any type of mast cell disease (see TMS for a Cure for more information.)

In a mast cell/mast cell activation related disorder, something has gone wrong with the mast cells. There may be too many of them, they could be irregularly shaped, or they could be degranulating—as in mast cell activation syndrome—and be over-active for unknown reasons. A person with a mast cell/mast cell activation disorder may experience severe and life-threatening reactions after exposure to even very small amounts of a chemical or substance. Individuals with mast cell activation related disorders need to avoid exposures to the chemicals and the triggers to which they react.

I’ve heard there’s a connection between mast cells and COVID—is this true?

Current research has shown that the COVID-19 pathology of infection is linked to an over-response of immune cells that include mast cells. Recent studies have also shown that mast cells are involved in the pathogenesis—the origination and development—of COVID-19: elevated numbers of mast cells as well as significantly higher levels of specific chemicals that indicates systemic mast cell activation in patients with COVID-19 who were studied (click here, here, and here to read the research articles.)

There is also current research on Long COVID and its link to mast cell activation symptoms (click here and here to read about this research.)

What does this mean?

Doctors (see J. Tsafrir, MD and T.C. Theoharides, MD) are urging that healthcare professionals (medical doctors, psychotherapists, psychologists, psychiatrists, social workers, nurses) be aware of mast cell activation syndrome (MCAS) and learn the presenting symptoms of mast cell activation related disorders. Recognizing and understanding mast cell activation and mast cell activation related disorders may suggest routes to effective therapy (click here to read article.)

What is Long COVID?

According to the World Health Organization, Long COVID refers to the array of long-term symptoms that some people experience after having COVID. Research has shown that as many as 50% of people who have had COVID report having Long COVID symptoms (see here). Symptoms include: fatigue, breathlessness, and cognitive dysfunctions such as confusion, forgetfulness, lack of mental focus and clarity (see WHO, 2022.) Symptoms can persist from when a person first gets COVID, or can develop after a person recovers from COVID, or can come and go or relapse over time and can affect a person’s ability to work and to perform activities of daily living (see here, here, and here)

Are mast cell disorders the same as chemical sensitivities or MCS?

Mastocytosis, mast cell activation syndrome (MCAS), systemic mast cell disorder are all medical diagnoses. Multiple Chemical Sensitivity (MCS) is not a medical diagnosis (see here). Mastocytosis, MCAS, and mast cell related disorders share many of the same  symptoms. These symptoms typically include chemical sensitivity. Current research (see T.C. Theoharides, MD, here and here) has shown that the reactions to triggers individuals experience, including being sensitive to multiple chemicals, have a basis in mast cell function and mast cell degranulation.

What do I do?

If you feel that you may have a mast cell related disorder, please contact a physician to receive medical help. The information presented here is not medical advice and is in no way a substitute for receiving medical advice and treatment from a doctor.


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