Functional Medicine for Mast Cell Activation Syndrome (MCAS)

What is mast cell activation syndrome?

Mast cells are immune cells that cause allergic reactions. They store or make chemicals called mediators. When something activates (switches on) the mast cells, they release these chemicals.^{1, 2}

In MCAS, a person has repeated episodes of the symptoms of anaphylaxis (a severe allergic reaction), such as hives, swelling, low blood pressure, trouble breathing and severe diarrhea. High levels of mast cell chemicals are released during these episodes.^{1, 4}

Experts describe three main types. In primary MCAS, the mast cells have a gene change that makes them release chemicals on their own. Mastocytosis is one condition of this kind. In secondary MCAS, normal mast cells are set off by something else, such as an allergy. When no cause is found, it is called idiopathic MCAS, which means the cause is unknown.^{1, 3}

MCAS is uncommon. Doctors still debate how MCAS should be diagnosed and when the term should be used. A considerable number of people are diagnosed with MCAS without solid proof that mast cells are causing their symptoms.^{2, 3}

Common symptoms of mast cell activation syndrome

MCAS symptoms come in separate episodes, or attacks. In most cases the episodes look like anaphylaxis. The symptoms are severe and affect two or more parts of the body at the same time.^{1, 2}

A lower, ongoing release of mast cell chemicals may also cause milder symptoms. But many symptoms linked to mast cells, such as flushing, itching, headache, belly pain or a fast heartbeat, are not specific to mast cells. Other conditions can cause them too.^{1, 2}

Symptoms during an episode can include:^{1, 2}

• Itching, hives, swelling, or skin that turns red (flushing)¹
• A fast heartbeat, low blood pressure, or fainting¹
• Wheezing, shortness of breath, or a harsh sound when breathing that comes with throat swelling¹
• Diarrhea, nausea with vomiting, and crampy belly pain¹
• Red eyes, or an itchy or stuffy nose²
• Nerve, muscle or joint symptoms, which are common but not unique to MCAS²

How mast cell activation syndrome is diagnosed and treated

Anaphylaxis-like symptoms can have other causes. So experts use set criteria to make sure that mast cells are responsible. Under the consensus criteria, all three of these must be true. First, you have typical, severe episodes that affect at least two body systems. Second, a blood or urine test taken during an episode shows a clear rise in a mast cell chemical, compared with your own baseline (usual) level. Third, your symptoms improve with medicines that target mast cell chemicals.^{1, 2}

This means the tests must be timed to your symptoms. A blood test for tryptase, a chemical made by mast cells, should be drawn between 30 minutes and two hours after an episode starts. A baseline level is drawn many days later. Urine tests for other mast cell chemicals may also be used.^{1, 2}

A high tryptase level by itself is not enough to diagnose MCAS. The level has to rise during an episode, compared with your baseline. These are not standard lab tests, so it helps to work with an allergist who can make sure they are ordered and done on time.^{1, 2}

If the criteria are met, more tests check for mastocytosis or a related condition. These may include a blood test for a gene change called KIT D816V and, in some cases, a bone marrow biopsy (a small sample of bone marrow).¹

Many other conditions can look like MCAS, including some heart, hormone, skin, gut, nerve and mental health conditions. Doctors need to consider these, and finding the answer can take time. Experts have also not agreed on other lab markers for MCAS.^{2, 3}

Treatment aims to relieve symptoms. Severe episodes are treated like anaphylaxis, starting with epinephrine when needed. Your allergist may also prescribe antihistamines (medicines that block histamine), medicines that block chemicals called leukotrienes, or other medicines. If these medicines do not help, that suggests MCAS is not the cause. Avoiding things that set off your mast cells is also part of care. There is no treatment yet that clearly makes MCAS go away.^{1, 3}

An allergist or immunologist has special training to diagnose allergy problems and to help you make a plan to protect yourself in the future.⁴

How our care fits alongside your allergist or immunologist

Avicenna Functional Medicine does not replace your allergist or immunologist or the treatment they prescribe. Our role is to add to your care, not to take its place.

In a functional medicine visit, we look at factors that may contribute, such as possible triggers of mast cell reactions, and we build a plan to help you manage them alongside your allergist or immunologist. Triggers differ from person to person. Triggers that experts list include certain foods and medicines, allergens in the environment, stress, lack of sleep, exercise, rubbing or pressure, and heat or cold.³

Please do not stop or change any prescribed medication without talking to the doctor who prescribed it. If you are at risk of anaphylaxis, carry the epinephrine your doctor prescribed, and fill out an anaphylaxis action plan.⁴

What to expect at Avicenna

All visits are by telehealth, for patients located in Florida and Texas. We are a cash-pay practice, and we accept HSA and FSA. Care usually follows these steps:

• A free, 30-minute discovery call to talk about your health and whether our approach is a good fit for you
• A full intake visit with our health coach, under clinician supervision, covering your history, symptoms, current treatment and goals
• Testing chosen for you, where it is likely to be useful
• A personalized plan, with follow-up visits to review how you are doing and adjust the plan as needed

When to get urgent care

In most cases, MCAS episodes take the form of anaphylaxis. Anaphylaxis is a serious, life-threatening allergic reaction. It needs medical treatment right away, including a prompt dose of epinephrine and a trip to a hospital emergency room.^{2, 4}

Warning signs of anaphylaxis usually affect more than one part of the body. They include hives or an itchy red rash; swelling of the throat or other areas; wheezing, chest tightness, trouble breathing or a cough; and a hoarse voice or trouble swallowing. Other signs are vomiting, diarrhea or stomach cramps; a pale or red face and body; passing out; or a feeling that something terrible is about to happen. A severe reaction can happen without any skin symptoms.⁴

If you think you are having anaphylaxis, use your epinephrine and call 911 right away. Do not take an antihistamine or wait to see if symptoms get better.⁴

Telehealth visits with our team are not for emergencies. Call 911 right away if you have warning signs of a medical emergency, such as:⁵

• Chest pain or pressure that lasts two minutes or more⁵
• Trouble breathing or shortness of breath⁵
• Sudden confusion, unusual behavior or trouble waking up⁵
• Fainting or passing out⁵
• Sudden dizziness, weakness or changes in vision⁵
• Being unable to speak⁵
• Severe belly pain, or sudden severe pain anywhere in the body⁵
• Coughing up or vomiting blood⁵
• Thoughts of suicide or of harming someone else (you can also call or text 988)⁵