I was diagnosed with MCAD and HIT by Immunologist Dr Seneviratne who, IMHO, is the only person in the UK to see if you have suspected Mast Cell Activation Disorder. He gave a lecture at EDS UK’s 2014 conference on mast cell disease and histamine intolerance and the link to EDS and other conditions such as POTS, and EDS UK have now placed a video of the lecture in the member’s section of their website.
Below is a summary of the salient points of Dr S’s talk, most of which were discussed with me at my appointment with him in 2013.
The immune system is made up of 3 components: white cells, antibodies and complement (which helps both the white cells and antibodies to work). Mast cells are a type of white cell which, historically, the body used to fight parasites. However, in modern times we now come into contact with very few parasites and the mast cell hasn’t got much to do. Consequently in some people it can start to misbehave, reacting to things it shouldn’t because it’s basically a bit bored (my words, not his!).
As an immunologist Dr S worked predominantly with people who had either allergies or immuno-deficiency, ie the immune system was having an IgE reaction to things like animal dander/pollen/nuts or under-reacting to things it should be fighting. However, he kept seeing patients who had immune reactions, particularly to foods, chemicals and drugs, but who didn’t fit the diagnostic criteria for either allergy or immuno-deficiency.
These patients were usually diagnosed with multiple chemical sensitivity but most doctors believed the symptoms were psychosomatic as conventional allergy tests showed they weren’t actually allergic to anything, with normal IgE results, normal tryptase levels and a normal amount of mast cells. The mast cells were, however, obviously ‘twitchy’ and reacting willy nilly to environmental situations they should just be ignoring.
Other Consultants around the world were seeing the same thing and, around 10 years ago, collaborated to introduce Mast Cell Activation Syndrome for these patients. This is now a recognised disease entity with strict diagnostic criteria.
About four years ago, Dr S began getting referrals of patients with MCAS from colleagues working in other fields and realized he was seeing a lot of people with both Ehlers-Danlos (hypermobile type) and/or POTS. There appears to be a link between these two diseases and MCAS but as yet no-one knows why.
Mast cells produce around 30 chemicals when they react, including histamine, prostaglandins and cytokines. Historically, histamine has been extremely difficult to measure as it starts to break down immediately after it leaves the body. Conventional histamine tests, where the sample sits on someone’s desk for hours, then is transported to a lab where it often isn’t tested for days on end, gives very unreliable results. Dr S, therefore, only uses one lab to test histamine following very strict protocols. This test measures:
- plasma histamine
- urinary histamine
- spot methyl histamine/creatinine ratio
- histamine releasing antibody
He also measures serum tryptase. In some people, all these tests will be normal yet they will still have symptoms of mast cell activation. In the past 12 months, Dr S has therefore arranged for serum PGD2, 24 hour urine PGD2 and leukotriene samples to be sent to the Mayo Clinic in America for testing, which often show evidence of mast cell activation even when histamine levels are within the normal range. He also recommends a gene test for the C-kit mutation because around 10% of people with MCAS will have a faulty C-kit gene (responsible for histamine activation).
Current drug treatment options for people with MCAS are poor and much more work is needed to find more effective medications. Current treatment consists of:
- Second generation H1 antihistamines, which should be given in high doses, up to 4 times the level used to treat conventional allergies. Doctors aren’t used to prescribing higher than normal doses of antihistamines, however it is safe and if they do a Google search they will see information confirming this. Do not use first generation H1 antihistamines, such as Piriton (chlorpheniramine) as they cross the blood brain barrier and can cause serious side effects if used long term, particularly in children.
- Mast cell stabilizers such as Sodium Chromoglygate (Nalcrom) or Ketotifen.
- Monteleucast, which blocks leukotrienes. This is used as a first line of treatment in the USA, but as it only blocks leukotrienes and not other mast cell mediators, Dr S prefers to try mast cell stabilizers first.
- If all else fails, patients often try supplements such as Quercetin. However, as there is no literature available on their safety and efficacy Dr S doesn’t prescribe these himself.
- Following a low histamine diet is important.
Histamine Intolerance (HIT) is a totally separate disease to MCAS, although it can produce almost identical symptoms. HIT is due to low levels of DAO in the gut. DAO is used to ‘mop up’ the histamine we all produce when we digest food, plus any histamine contained in the food itself. When DAO is low it can’t deal effectively with this digested histamine, which builds up in the body to produce toxicity. Some people have MCAS only. Some people have HIT only. While others have both MCAS and HIT.
Some patients will test negative for histamine, PD2 and leukotrienes yet still have mast cell activation symptoms. Mast cells produce around 30 mediators and we currently only test for a handful of these. If all evidence points towards MCAS, Dr S will do a trial of antihistamines and mast cell stabilizing drugs and see how the patient responds. It is recognized, however, that many people with MCAS tolerate drugs poorly, if at all.
As a patient it’s brilliant to see that, finally, MCAS is being recognised and the link between mast cell activation and EDS has been discovered. However, there is a long way to go in terms of educating the mainstream medical profession on mast cell activation and this will include turning long held beliefs on the way the immune system and mast cells work on its head. We also have to find more effective treatments, particularly for those of us who have mast cell reactions to currently available drugs. “The journey of a thousand miles begins with one step.”