MCAS, also known as mast cell activation syndrome, is a condition in which there is an inappropriate release of various chemical mediators called mast cells. Many people, including physicians, mistakenly refer to these symptoms as histamine intolerance. Mast cells are a part of the immune system and are responsible for releasing these mediators to protect the body against foreign invaders. They are concentrated in areas where the body comes into contact with the external environment, such as the gastrointestinal tract, nose, mucous membranes, lungs, and skin.

However, there is an underlying cause (or causes) that increases the risk of developing mast cell activation syndrome for many individuals. Some people are more prone to releasing the mediator contents of mast cells.
Factors contributing to MCAS include:
Furthermore, certain stimuli prompt mast cells to degranulate and discharge mediators in individuals who are prone to it.
Causes of MCAS are:
Receive a thorough examination to comprehend the essence of MCAS and gain a deeper understanding of the crucial data derived from published research studies on MCAS. Additionally, I impart my firsthand knowledge in managing MCAS within this article. With the objective of enhancing the result of your symptoms or ailment, this article strives to furnish you with valuable information that you can utilize (or present to your doctor).
Mast Cells Release Bioactive Substances
Nerve endings can be damaged and a proteolytic enzyme called tryptase can cause a unique physiological reaction in the surrounding tissue. Other mediators include cytokines, leukotrienes, prostaglandins, heparin, and tryptase. Histamine is the most common mediator released from mast cells in response to allergens such as pollen. Inside a mast cell, there are tiny sacs called granules that contain a couple hundred chemical mediators which are released when triggered by a toxin or allergen binding to the mast cell.
Who is Prone to Mast Cell Activation Syndrome?
The development of risk in MCAS is increased in individuals with genetic variations and repeated exposure to allergens, toxins, and chronic infections, leading to immune dysfunction in people who have developed it. There is a potential for anyone to develop mast cell activation syndrome, as mast cells are present in all humans.
Other surveys have confirmed a rise in the occurrence of MCAS. Obtaining a proper diagnosis may require a significant portion of an individual’s time and resources, as MCAS is often implied by its symptoms. On average, it took 30 years for individuals to receive a diagnosis of MCAS, with the most frequent onset of symptoms occurring in individuals around the age of nine. Women constituted 69% of patients diagnosed with mast cell activation syndrome, with 75% of them being Caucasian. A study reported specific characteristics and a prevalence rate of MCAS in over 400 patients.
Signs of Mast Cell Activation Syndrome
Physicians face a challenging task in diagnosing mast cell activation syndrome (MCAS) due to its multifaceted involvement across multiple systems and symptoms. MCAS is not widely recognized because its symptoms can occur in every organ system, as mast cells, located throughout the body, contain over a hundred inflammatory compounds. It is common for children to be told by their pediatrician that they will “outgrow” their symptoms. However, many people only realize that their childhood symptoms were related to MCAS after receiving a diagnosis in adulthood.
The most frequent indications of MCAS are:
Disorders Linked to Mast Cell Activation Syndrome
There are several conditions associated with mast cell activation syndrome, making it difficult to distinguish if the symptoms present are caused by MCAS or a similar disease or illness.
Conditions linked to Mast Cell Activation Syndrome (MCAS) encompass:
Mast Cell Activation Syndrome in Gastrointestinal Disorders
Leaky gut syndrome and eosinophilic esophagitis, SIBO (small intestine bacterial overgrowth) and IBS, are gastrointestinal disorders linked to MCAS. Mast cell activation in the gut, whether provoked by food allergies, parasites, or bacteria, can cause symptoms such as heartburn, queasiness, throwing up, irregular bowel movements, and diarrhea. Mast cells, which are abundantly found in the digestive tract, safeguard humans against any foreign intruders they might ingest.
The researchers published their findings on a group of patients who were tested for persistent IBS-like symptoms after experiencing activation of mast cells in the gut, known as SIBO and MCAS syndrome. Among these patients, the most common symptoms were abdominal pain (87%), bloating (75%), constipation (67%), nausea (62%), and heartburn (54%), which they had before experiencing any other symptoms of MCAS. The authors concluded that SIBO was present in 31% of patients with MCAS, and that altered digestive motility could contribute to SIBO in the gut through the release of mast cell mediators.
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In my experience, when mast cell activation and leaky gut syndrome are effectively treated, individuals can consume a wider range of foods in their diet without experiencing any negative responses. Leaky gut syndrome, also known as small intestine inflammation, occurs when food particles easily pass through the intestinal barrier and enter the bloodstream, triggering an immune response. Additionally, heightened mast cell activity can lead to heightened inflammation in the small intestine.
High Histamine Foods.
The alleviation of MCAS symptoms is associated with the decrease of high-histamine and histamine-releasing foods. Within your body, specific foods trigger a response. To assist you in determining which foods elicit a response, here is a comprehensive list for your reference. The release of histamine from mast cells can be induced by particular foods or those that have high levels of histamine.
Foods that are rich in histamine
Foods. that cause histamine release
Lyme Disease is Linked to Mast Cell Activation Syndrome
Mast cell activation syndrome may play a role in the presence of various pathogens including viruses, bacteria, fungi, and parasites. The immune system reacts by triggering mast cells in an effort to safeguard the human body from the pathogen.
People may require treatment for mast cell activation syndrome in severe cases of MCAS when they encounter negative responses unrelated to Lyme disease infections and the medications prescribed for Lyme disease. Effectively treating MCAS can provide clarity on the remaining symptoms of Lyme disease, resulting in improved well-being for the patient and addressing the overlapping symptoms between MCAS and Lyme disease. Additionally, approximately half of the patients I encounter who have tickborne infections also experience MCAS.
If the infections are provoking the release of mast cell mediators, it is crucial to screen for Lyme disease and related infections in order to identify the specific infections. I prefer to tackle the treatment of illnesses and diseases by addressing the underlying cause. A scientific study validated that the activation of mast cell degranulation triggers the bacteria that leads to Lyme disease. MCAS is a component of the immune dysregulation and plays a role in the manifestation of symptoms when Lyme disease – or other infections – and mast cell activation syndrome coexist.
Mold Exposure can Trigger Mast Cell Activation
Enhancing the result of mast cell activation syndrome aids in dealing with mold toxicity. It is crucial to conduct thorough testing for mold illness in such situations. If an individual is experiencing any MCAS symptoms, it is assumed that they have been exposed to water-damaged buildings or environmental mold. Mold and mycotoxins are also linked to mast cell activation syndrome. Human exposure to environmental molds and their toxins (mycotoxins) can lead to immune dysfunction and immune suppression.
Identifying Mast Cell Activation Syndrome
Lawrence Afrin and Gerhard Molderings delineate the diagnostic criteria I employ in my clinical practice for mast cell activation syndrome. Medical practitioners, mast cell investigators, and institutions have put forth various diagnostic criteria for mast cell activation syndrome. The physician ought to request laboratory examinations to validate this suspicion since the clinical manifestations of mast cell activation syndrome should provide them with hints.
The phlebotomist in the laboratory needs to be aware of the need to avoid testing Tylenol, Advil, NSAIDs, and proton pump inhibitors (such as Prilosec and Prevacid) before five days, etc. Additionally, they need to keep the samples chilled at the time of blood draw and transport them in a cooler to the lab. The samples should be kept in a refrigerator once they arrive.
Collecting samples during a flare of MCAS symptoms can be challenging, as even elevated levels of one mediator due to the timing of mast cell degranulation can be difficult to observe if the specimens are not properly handled.
The diagnostic evaluation for MCAS includes:.
Click here to download and print a list of MCAS exams and handling instructions for your doctor or laboratory.
Could it be Mast Cell Activation Syndrome?
Mast cells are an essential part of our immune system and are located throughout our bodies. There has been an increased incidence and awareness of mast cell activation syndrome in the past decade. If you have consistent symptoms with MCAS, it is necessary to properly test for the above mediators. There may be underlying causes of mast cell activation syndrome, including other environmental exposures and infections, exposure to mold, and toxins. It is important to identify the potential causes with proper testing in order to improve the outcome of treating mast cell activation syndrome and improve symptoms.