• Mast cells are part of the immune system. They’re found throughout the body. Mast cell activation disorder (MCAD) refers to an increased number of mast cells, increased activity of mast cells, or both. When people are exposed to allergens, including medications, foods, and toxins mast cells typically react by releasing chemical mediators. These mediators cause symptoms of an allergic reaction, including itching, mucus, and inflammation. Mast cells are best known for their role in immediate IgE-mediated, allergic responses in anaphylaxis, food allergy, venom allergy, and asthma.
• Recent reports have also implicated mast cells in nonallergic disorders, including headache syndromes, irritable bowel syndrome, non-celiac gluten enteropathy, osteoporosis, autoimmune syndromes, neuropsychiatric disorders, and interstitial cystitis.
• Milner et al. identified families with an elevated, baseline serum tryptase, which was associated with the triad of dysautonomia, MCAD, and joint hypermobility.
• Reported secondary causes of mast cell disorders include comorbid immune disorders, including classic atopic syndromes (“allergies”/ IgE receptor-mediated MC activation); autoimmune disorders (autoimmune chronic urticaria, multiple sclerosis, rheumatoid arthritis; and chronic infections, of which some likely occur in the context of primary immune deficiency disorders.

The proposed diagnostic criterion for MCAS: Chronic/recurrent symptoms

1. Skin: flushing, pruritus, urticaria, angioedema,
2. ENT: nasal congestion, throat swelling
3. Lungs: wheezing,
4. Headache
5. CV: hypotension
6. Gut: Abdominal symptoms +/- diarrhea
7. Absence of any other known disorder that can better account for these symptoms

Treatments for mast cell activation disorder may include medications supplements and lifestyle changes.