Mast cell activation syndrome

Mast cell activation disorder (MCAS) is a disorder where mast cells are normal in number, but release excessive amounts of chemicals known as mast cell mediators including histamine. The symptoms of MCAS can also be very similar to that of myalgic encephalomyelitis (ME) and therefore may be confused. It is also possible to have ME and MCAS disorders simultaneously.

Signs and Symptoms
In MCAS, the body's mast cells are being created in normal number, but are over-responsive to dietary or environmental triggers. Both of these situations might lead an individual to have excess histamine in circulation. Excess histamine can cause severe inflammation and a wide variety of symptoms. Almost any organ system in the body can be affected by MCAS. Because a variety of symptoms can be present MCAS is commonly misdiagnosed.

A confounding element in diagnosing MCAS is that signs and symptoms occur in almost all areas of the body. The symptoms might wax and wane

Most patients experience fatigue, fevers, and sensitivity to individualized environmental "triggers." Other commonly identified signs and symptoms are as follows :


 * hot flashes, irregular heartbeat, high or low blood pressure (hypotension and/or hypertension)


 * vertigo, dizziness, forgetfulness, depression or anxiety, headache s, insomnia, restlessness


 * hives or other visible skin rashes


 * arthritis, muscle pain, bone pain, osteoporosis/osteopenia


 * anaphylaxis (a severe allergic reaction)


 * Malabsorption and gastrointestinal distress leading to low iron and low Vitamin D and low B12

Diagnosis
MCAS can be difficult to diagnose as the cause of the syndrome is still considered to be unknown. In 2010, a criteria for diagnosing MCAS was proposed by Dr. Cem Akin and colleagues. These criteria suggest that two or more organ systems must be affected; this can include gastrointestinal, cardiovascular, skin, or respiratory. If given histamine or mast cell therapy, the patient's symptoms must improve. Thirdly, the patient should be tested for serum tryptase an enzyme secreted by mast cells during the peak of a symptomatic episode. If tryptase is >15ng/mL the patient may have MCAS. Urine and blood tests should be collected more than once to confirm a positive diagnosis. Prostaglandin and histamine levels can be also be tested.

Comorbidities
MCAS is often diagnosed in patients that have been previously diagnosed with Ehlers-Danlos syndrome (EDS), a heritable connective tissue disorder and postural orthostatic tachycardia syndrome (POTS), a form of orthostatic intolerance. Both of these conditions are also commonly co-morbid with ME. The overlap between EDS, POTS, and MCAS is thought to be due to increased tryptase production.

An extra copy of the gene TPSAB1 has been noted as a possible cause for increased tryptase production. This gene has also been implicated in many other immunological diseases including autism, fibromyalgia, and chronic Lyme disease.

Common Treatments
Vitamin C has been noted to reduce blood histamine levels. Magnesium deficiency has been seen to increase mast cell production in some cases; therefore magnesium supplementation may be helpful in controlling mast cell division.

Over the counter antihistamines such as Allegra, Zyrtec, Claritin, and Ketotifen are a common treatment for MCAS. It is recommended that the patient should consult a physician for secondary symptom treatment or targeted mast cell therapies. Some patients also use herbal antihistamine supplements such as quercetin or diamine oxidase (DAO), an enzyme normally produced by the body that breaks down histamine.

Prescription drug treatments include Xolair (Omalizumab), which has been proposed as a possible mast cell stabilizer and is used in allergic asthma and chronic urticaria. There is some limited evidence that sauna may be useful in antihistamine resistant urticaria, an allergic skin condition that involves mast cell activation and the production of excess histamine.

Doctors
There are a very few mast cell specialists working in the United States. An expert is Dr. Lawrence Afrin formerly at the University of Minnesota now in in Armonk, NY. Drs Clem Akin and Mariana Castells run a mastocytosis clinic at Brigham and Women's in Boston. More integrative doctors are beginning to be aware of mast cell activation syndrome, but it remains elusive in both treatment and diagnosis.

Triggers
Emotional or physical stress, many foods, and environmental factors can trigger mast cell degranulation. It is likely that each individual will have his or her personal triggers.

Learn more
Mast cell activation syndrome, Wikipedia


 * Molderings GJ, Brettner S, Homann J, Afrin LB. Mast cell activation disease: a concise practical guide for diagnostic workup and therapeutic options. Journal of Hematology & Oncology. 2011;4:10. doi:10.1186/1756-8722-4-10. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3069946/)