For people suffering from Orthostatic Intolerance, Postural Orthostatic Tachycardia, Mast Cell Activtation or EDS. Follow me as I document my struggle towards better health.

Mast Cell Disorders and POTS - Part II

If you have been diagnosed with Postural Orthostatic Tachycardia and/or Orthostatic Intolerance have you ever noticed that your digestive system can get uncomfortable and your body just doesn't like certain foods?  Have you been diagnosed with IBS or do you suspect you have Celiac Disease?  Do you feel better when you eat very simple foods such as proteins and veggies?  Are you sensitive to scents and perfumes? Do you react poorly when taking certain medications?

If you answered yes to any of these questions then investigating whether you have a mast cell disorder may be warranted.

What are mast cells?
According to Theo Theoharides from the Tufts School of Medicine:
Mast cells derive from the bone marrow and migrate into connective and mucosal tissues (Galli, 1993), where they are located at strategic points around capillaries close to nerve endings (Theoharides, 1996). Mast cells are critical for allergic reactions where the stimulus is immunoglobulin E (IgE) and specific antigen; however, there are also other nonimmune mast cell triggers that include anaphylatoxins, kinins, cytokines, as well as various neuropeptides (Baxter & Adamik, 1978; Coffey, 1973) such as somatostatin (Theoharides & Douglas, 1978), neurotensin (NT) (Carraway et al., 1982) and substance P (SP) (Fewtrell et al., 1982). When stimulated, mast cells synthesize and secrete numerous vasoactive, nociceptive and inflammatory mediators (Galli, 1993) that include histamine, kinins, prostaglandins, leukotrienes, cytokines, as well as the proteolytic enzymes chymase and tryptase (Schwartz, 1987). 
Mast cell disorders are still rather poorly understood.  As an Immunologist from Brigham & Women's said, "Our current level understanding of mast cells is similar to how well we understood T-cells in AIDS twenty years ago.  However, there is more research being done now which is very helpful in increasing our knowledge ."

How to find out if you have a Mast Cell Disorder?
The "gold standard" of diagnosing mast cell conditions used to be a serum tryptase test.  This is a blood test that can be requested by your family doctor.  Not many labs actually do tryptase tests so your blood sample could be sent as far away as the Mayo Clinic for investigation.  Tryptase is an enzyme which is produced by mast cells when they degranulate along with histamine and other substances.  An elevated tryptase result could indicate that your mast cells are busy and active.

However, researchers and specialists in mast cells now know a normal tryptase test does NOT rule out a problem with your mast cells.  Here is a link to a article published in the Journal of Hemotology by Molderings, Brettner et al in March of 2011 which not only describes the variety of mast cell misbehaviour but also diagnostic criteria and treatment options.

Does that mean I don't have to exercise anymore if my POTS or OI is related to a mast cell problem?
Whether your POTS is caused by mast cell problems or the cycle of the moon, evidence suggests that maintaining adequate blood volume and increasing your cardiovascular health through a specific program like the Levine protocol will help ameliorate the symptoms of POTS.

Unless you doctor specifically recommends you do not exercise because of some other reason other than you suffer from POTS or OI then you should really consider contacting the Levine team to see if you are eligible to participate in their study (I believe they are still accepting patients).

Mast Cell Disorders and POTS - Part I

Last April as I was happily performing my exercises as per the Dr. Levine protocol my blood pressure crashed.  Up until then I was feeling pretty good: my POTS symptoms were diminished thanks to the exercises and lotsa salt diet and I was looking forward to an awesome summer.

At the time of the crash I was using a rowing machine, I had my Garmin heart rate chest strap on and was tracking my heart rate using iCardio (DigiFit) on my iPad.  Twenty minutes into the exercise the bp crash occurred and I fell off the rowing machine.  The same blood pressure crash occurred the following day and the day after that.   The crash did not seem to occur when my heart rate increased rather it crashed after the increased heart rate was sustained for >5 minutes.This new symptom was perplexing because previous to then I had not had a blood pressure crash while sitting and exercising (rowing).

I emailed Dr. Levine's team describing these events.  The response was as follows: 1) these events are not consistent with typical POTS, and 2) they are probably not due to a structural defect with the heart (I was thoroughly checked for this).  Intriguingly I was asked if developed hives or shortness of breath while exercising.  I didn't but the question led me to investigate exercise anaphylaxis.
Exercise Anaphylaxis: Def - A form of allergy manifest by a sensation of skin warmth, pruritis and erythema, urticaria, hypotension, upper airway obstruction DiffDx Cholinergic urticaria, anaphylaxis.  Websters Dictionary
Well, it just so happens that a group at Brigham & Women's Hospital is conducting a clinical study on exercise anaphylaxis.  This group specializes in immunology, and more specifically, mast cell disorders.  I called one of the researchers and gave her my abbreviated medical history (the long form of the history takes several hours) which she kindly listened to.  She suggested that based on my history of POTS and anaphylaxis as a child I be investigated for a mast cell disorder.

Can mast cell disorders cause POTS?  The answer to that question appears to be yes.  In an article entitled Understanding the Mechanisms of Anaphylaxis by Richard D. Peavy and Dean D. Metcalfe from the Laboratory of Allergic Diseases, NIH they talk about when mast cells are activated producing histamine.
 Histamine stimulates vasodilation, and increases vascular permeability, heart rate, cardiac contraction, and glandular secretion.
Sudden vasodilation causes blood pressure to crash and people to fall off rowing machines.  Mast cell disorders and POTS...a worthy line of investigation for someone looking to get at the root cause of their POTS!!