What the Hist? Part 1 Basics
What do I mean by histamine issues?
MCAD / MCD
MCAS
MCS
HIT
Idiopathic Ucarteria
Beyond this post series, some good resources for learning more about mast cell issues include:
The Mast Cell Disease Society
Hospital Princess
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Mast Cell Activation Disorders / Mast Cell Disease
An inclusive label of immune disorders that involve symptoms caused by mast cell activation, when mast cells are triggered to release chemicals and produce an immune reaction.
The diffent forms of MCD are
Systemic mastocytosis (SM) Cutaneous mastocytosis (CM) Smoldering mastocytosis (SSM)
Mast cell activation syndrome (MCAS)
Hereditary alpha tryptasemia (HaT)
And advanced disease variants
Mastocytosis is caused by over proliferation of mast cells and can progress into cancer in the form of mast cell leukemia.
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Mast Cell Activation Syndrome
Disease that causes idiopathic (aka no known cause) activation of mast cells.
Symptoms include: Flushing, pruritis (itching), urticaria (hives), headache, gastrointestinal symptoms (including diarrhea, nausea, vomiting, abdominal pain, bloating, gastroesophageal reflux), tachycardia and hypotension (low blood pressure)
Diagnosis requires 3 parts:
Symptoms involving 2 or more organ systems simultaneously
Lab tests showing elevated mast cell mediators during acute episodes of symptoms
Response to medications that either: limit histamine (antihistamines), limit other mast cell mediators (leukotriene receptor antagonists), or block the release of mast cell mediators (mast cell stabilizers)
Patients who suspect MCAS should ask their doctor for a blood test request for mast cell mediators like serum tryptase and then go in for that blood test when symptoms start. The timing of the test is very important. If you aren't at the start of a reaction your levels might be normal even if you have MCAS.
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Multiple Chemical Sensitivity
A controversial diagnosis often used by functional and holistic practitioners for patients who have negative physical reactions to chemical exposure.
While symptoms are often non-specific such as headache, fatigue, malaise and so on, they can also include rashes, asthma and gastrointestinal symptoms indicative of histamine overload.
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Histamine Intollerance HIT
Catch all term for people with any disorder that causes sensitivity to histamine and inability to break down histamine. This may be due to an inability to produce DAO.
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Idiopathic Ucarteria
Hives of unknown origin
May or may not be related to mast cell dysregulation
Diagnosed by frequent hives over 1 month and no known cause
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Anaphylaxis
A potentially life-threatening allergic reaction in which hives, swelling of the throat and many other symptoms are present. May be caused by histamine/mast cell issues or an acute allergy (IgE allergy)
Symptoms include:
Fainting, light-headedness, low blood pressure, dizziness, flushing, difficulty breathing, rapid breathing, shortness of breath, or wheezing, hives, swelling under the skin, blue skin from poor circulation, or rashes, nausea or vomiting, fast heart rate, feeling of impending doom, itching, tongue swelling, difficulty swallowing, facial swelling, impaired voice, and mental confusion
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Severity
MCAD and MCAS are generally considered most severe due to being most likely to cause anaphylaxis. However, all other labels listed besides idiopathic ucarteria (which refers specifically to skin reaction) can also potentially cause anaphylaxis. While MCS has less stringent diagnostic criteria than MCAS but that doesn't mean that it is always less severe. The doctor you go to may have bias towards diagnosing MCS (functional/holistic) or MCAS (immunology).
It is important to remember that severity may vary greatly based on treatment, diet, and lifestyle. Someone may have very severe histamine sensitivity but by avoiding triggers obsessively rarely experience reactions. Others may have more mild issues but be in a situation where avoiding triggers is impossible, or triggers are unknown leading to stronger symptoms.
The amount of medication someone has access to also greatly affects sensitivity. For example, someone may be able to eat most foods but only due to require biologic injections. Whereas someone else may have to eat a very restricted diet because they only have access to OTC antihistamines.
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Misinformation
There is a lot of pseudoscience or unsupported evidence in histamine intolerance forums and discussions. In particular, people's triggers tend to be unique so it is important not to take one person's word for what is a "dangerous" food or product. It is also important to remember that stress is a major trigger for mast cell activation and histamine production. So if you are terrified of a certain trigger exposure may cause a reaction even if you are not reacting to the trigger itself.
The definition of different histamine disorders in particular MCS also frequently varies between practitioners (thus the non-specific definition given here). This series will focus less on definitions and more on the common treatments issues faced by people with any sort of histamine reactivity.
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Part 1 Definitions MCAS, MCAD, MCS, HIT, chronic hives, asthma the world of mast Cell Activation and histamine intolerance is big and confusing. Mast Cell issues are a common comorbidity to Myalgic Encephalomyelitis or MECFS and related complex Chronic Illness. Yet the factual information about these diseases is often conflicting and difficult to decipher. This is the first of a 6 part series attempting to provide an intro into mast cell and histamine issues for other people with ME / CFS.
My experience of histamine intolerance followed by idiopathic Urticaria and now MCAS has been filled with misinformation, unknowns, and conflicting advice. My goal with this series is to provide my best interpretation of the available data. I am not an expert, nor a doctor, simply a patient with a passion for scientific accuracy and evidence-based medicine.
I firmly believe in listening to patients and trusting people's accounts of their own experiences. However, I also know that misinformation can easily spread in the chronic illness community when everyone so desperately wants solutions and answers to questions that research has not yet uncovered.
I hope to provide both basic facts about mast cells and histamine we know to be true as well as serve the community by pointing out the ways in which our personal deductions can be skewed. My goal is to support other patients like me in learning the science around mast cells and histamine and applying the scientific method in order to better advocate for our health.
Like MECFS, histamine disorders are poorly understood by many doctors. It often falls on patients to self-advocate and push for appropriate diagnosis and treatment. This post can help you to identify whether you suffer from histamine disorders, mild or severe. Unlike in ME, many medications exist to treat histamine disorders. The next post in this series will address medication management and treatment of histamine disorders.
