Histamine levels always elevated in MCAS?

Since I have a lot of auto immune, and under immune, I should periodically test for MCAS.

Am I right in thinking if you have MCAS you will have elevated blood histamine?

Oh good, the functional MD had that one done and it looks good. It has a limit vs a range. (Now I know what that was for)

HOMOCYSTEINE,TOTAL:

Normal range: below <15.0 umol/L
Value 7.1

No, testing for MCAS is extremely poor. The best way to determine whether it's part of the picture for you is to remove histamine triggers and/or try multiple types of antihistamines concurrently, and see if symptoms improve for you. This probably isn't true for everyone, but for me it was quite obvious that removing histamine triggers resolved symptoms right away.

Testing for MCAS is complicated and still evolving. It's not so easy to print out a paper and bring it to your primary care physician (or LLMD) and ask for either consensus-1 or consensus-2 bio-markers to be tested for. (A lot of doctors don't like to run any test that they can't interpret.) This paper probably won't be super helpful in any practical way, but this will at least give you a peek at what the foremost experts on MCAS are saying about diagnostic testing--at least as of three years ago.

2021 paper co-authored by Dr. Afrin about MCAS diagnosis.

https://www.mastcellaction.org/assets/_/2021/09/15/6e63c4e5-117c-44cf-a84e-5ff018b6721d/2194802x-diagnosis-diagnosis-of-mast-cell-activation-syndrome-a-global-consensus-2-1.pdf

Quote:
The consensus-1 proposal asserts (though seemingly without evidence) that a rise in serum total tryptase
by “20% + 2” ng/mL is a preferred marker of MCA, though if a patient cannot be shown to have “20% + 2,” then elevations in a few other relatively MC-specific mediators can be considered diagnostic. These other mediators include prostaglandin D2 (PGD2 ) or its immediate 11-β-PGF2α metabolite, and urinary histamine metabolites [generally taken to be just N-methylhistamine (N-MH) as N-methyl-imidazolacetic acid (MIMA) is no longer readily testable at clinical laboratories, at least in the United States]. The “consensus-2” proposal states that levels of a slightly wider range of mediators relatively specific to the MC [tryptase, chromogranin A (CgA), heparin, PGD2 , histamine, N-MH, 11-β-PGF2α, and leukotriene E4 (LTE4)], which rise above their normal ranges can be taken as diagnostic laboratory evidence of MCAS in the proper clinical context of other-
wise unexplained chronic multisystem issues of generally inflammatory ± allergic ± dystrophic themes. Like tryptase, heparin is highly (though not perfectly) specific to the MC [58], and some published research now suggests an elevated plasma heparin level likely is the single most sensitive marker of MCA, with approximately 80% of patients clinically demonstrating symptoms consistent with MCA showing increased levels of plasma heparin when measured using a sufficiently sensitive assay [58]. In clinical practice, the biological and logistical challenges of measuring heparin need to be addressed to ensure accurate
results.
End quote

Comment:
A spectrum of MCAS type issues run in my family on my mother's side. The spectrum includes everything from Ehlers Danlos, to fibromyalgia. A history of mold exposure is common to everybody as well. And another thing that they all have in common is IBS. Asthma is common but not always present. But IBS is always present for everybody I know in my family who has serious struggles with MCAS related problems. And everybody has serious mold exposure at one or more residences of their past. (Mold is a sensitizer to other allergens. So is formaldehyde, another source of indoor air contamination in some residences, especially trailers, but also any houses that don't have boiler or furnace exhaust properly vented, plus simply brand new houses.)

Even without MCAS it is still possible for mast cells to play a role in setting up a positive feedback loop that keeps inflammation going. Mast cell involvement is being studied in MS and neuropathy. Mast cells are even involved in non-healing diabetic food wounds. Mast cells are being increasingly studied beyond allergies and even beyond MCAS.

Many people on herbal protocols for Lyme are probably already taking herbs that have some degree of mast cell stabilizing activity. The resveratrol in Japanese Knotweed is one example. The baicalin in Chinese Skullcap is another.

It's still early. He's on day four today, only starting out at 1/4 of a dose. Then on Friday he'll increase to 1/2 of a dose. The very first night I gave it to him, he looked drowsier faster than usual. The next two nights he was just as wide awake as usual at bedtime. I haven't noticed anything else yet. I think Ketotifen takes weeks to get mast cell numbers down in tissues (in cases where they aren't just abnormally activated continually but are also recruited in unusually high numbers). A study of pediatric IBS showed that the entire digestive lining, from esophagus to stomach to small intestine to colon, was full of an abnormal recruitment of mast cells in unusually high numbers! No way to know if that describes him or not, but maybe it could! I'm going to give it all summer before I decide how well it worked. Nothing else added all summer. Nothing else taken away all summer. (Not without a very good reason.)

This is more practical and easier to follow than the paper I linked to. It's an interview with Dr. Afrin. He says in the interview that some MCAS patients don't have a speck of allergy to them.

"And the universal constant that I’ve been observing with mast cell activation disease actually is chronic inflammation. And then, beyond the chronic inflammation, there may or may not be various allergic-type phenomena in the individual patient with this disease. And there also may or may not be assorted abnormalities of growth and development in, well, potentially any tissue really."

https://drruscio.com/mast-cell-activation-syndrome-clinician-researcher-dr-lawrence-afrin/

Wow, thank you pinkblossom!