Hello For 8 months I've struggled with a range of health issues with literally every kind of test revealing no diagnosis (range of bloods, xrays, ultrasounds, CTs etc). The range of symptoms are those which I've read are associated with mast cell issues. The specialists have concluded it must be a chronic fatigue/post viral fatigue issue purely because nothing else could be identified. Ironically fatigue is not one of my main symptoms. Some of my symptoms have stayed the same for 8 months, whereas others have come and gone over time, or change in their severity. I probably feel the best I have in months and months, which I'm happy about, but I'm 'not the same' compared to before this all started. About 6 weeks ago I had a tryptase test (taken on a day where I felt well) and the result as encouraging (it was only 3 which is VERY low). I just got my results for a 24 hour urine methyl histamine test which I had taken around 2 weeks ago and the result was above the normal range, but not by much (the result was 2.1 and I understand the upper limit of the normal range is normally around 1.5 or 1.8). I'm now waiting to see a specialist but my question is, does the low tryptase definitely rule out mastocytosis, and combined with the slightly elevated methyl histamine result, does this suggest that if anything, it would most likely be a mast cell activation issue? I've had a RAST test for Inhaled Allergens and Staple Food Mix and this test did not reveal any allergies. Since becoming unwell, I've been diagnosed with gastritis, reflux, low vitamin d, high cholesterol and calcium levels in my blood, even though I don't have a high calcium diet. My unerstanding is these are all commonly associated with mast cell issues. I did read that slightly high methyl histamine can sometimes occur in a 'healthy' person, however given my other symptoms (I can list them if anyone is curious or thinks it may help the community), it makes me think there has to be a connection.