Following my appointment with Dr Seneviratne on Tuesday, I’m now waiting to have some tests carried out to determine my histamine load. Luckily I’d already had many allergy-type tests done (skin prick for allergens, total IgE, tryptase, inflammatory markers, routine blood work like cell counts etc.) when I had my NHS Immunology appointment at Preston in June and my GP had sent copies of the results to Dr S with my referral letter, so these didn’t have to be repeated. I’ve also already had an endoscopy and been tested for Coeliac Disease and H-Pylori infection (both were negative) and a full abdominal MRI scan (also clear).
Dr S explained that he no longer recommends a 24 hour N-methlyhistamine urine test, as he found this could not be standardized and therefore results were unreliable. Instead he now orders a spot urine test, in which the histamine:creatinine ratio is measured. This is a very specialized test, in which the urine has to be immediately frozen to preserve histamine, and currently only available at The Doctor’s Laboratory in London (a private lab which can only be used by medical staff). There is, however, a branch of The Doctor’s Lab in Manchester, which would be much easier and closer to home for me, so he is in the process of enquiring if they have the equipment and knowledge to do the test there, but did explain that if there was any doubt I’m better travelling all the way to London as at least then I’m guaranteed a reliable result.
The second test he’s ordered is for DAO. I was unaware that this was available in the UK, so am extremely pleased it can be done here. This test measures levels of Diamine Oxidase, a stomach enzyme which breaks down the histamine present in the foods that we eat. Low DAO indicates Histamine Intolerance (HIT). Having been on a low histamine diet now for 6 months I’d be surprised if there was a problem with my DAO levels, but you never know and it will be interesting to see the results.
I was hoping to start trying a Vitamin C supplement next week, as although the H2 antihistamines I’m currently taking for my stomach acid stop histamine binding to mast cells they don’t deal with the histamine itself, which continues to float around in the body causing symptoms. Vitamin C actually destroys histamine (one molecule of Vitamin C destroys one molecule of histamine), although it does have to be taken in high, divided doses throughout the day as it’s very quickly excreted through urine. However, Dr S has advised I take no more drugs or supplements until I’ve had all my tests done. I forgot to ask him if I should continue on a low histamine diet, or maybe stop it a week before the tests are due – I’ll have to email his PA to ask.
I admitted to Dr S my worst fear is that the tests will come back fine (in 20 years of being incredibly ill, I have never ever had a test come back abnormal, even when I was told I was critically ill and might not make it through the night). However, he reassured me that my history and symptoms all point very definitely towards MCAD and that if the tests came back fine I simply need them repeating when I’m more symptomatic, or at regular intervals until we catch the histamine (I’d probably aim for spring, when the pollen season begins and I usually have a good 2 months of hives). Watch this space!
I’m feeling pretty nauseous with the stress and fatigue of the past week, so am drinking copious amounts of fresh ginger tea (a natural anti-histamine and anti-emetic). See the Miscellaneous section of the Recipe Page for details and scroll down.