Doctor says I have Mast Cell Activation Syndrome

On of my doctors (Dr. M) has been encouraging me lately to get tested for Mast Cell Activation Syndrome (MCAS).  MCAS has been, of course, discussed heavily in ME circles in recent years.  Last year I read Dr. Lawrence B. Afrin's book on the subject, Never Bet Against Occam, which is considered by some to be the best book on the topic.  My only conclusion from reading the book was that the entire field of MCAS seemed too nascent and undeveloped (especially at the time of the writing of Dr. Afrin's book in 2016) and that we (ME patients) would need to wait for further research for anything useful to come out of this new topic of research.  For one, the list of ailments that Dr. Afrin attributed to MCAS at the end of his book might as well be the entire Physician's Desk Reference—it seemed (and still seems) unlikely that nearly every ailment ever acknowledged in western medicine (a little bit of hyperbole here) would have MCAS as its root cause.

Nevertheless, Dr. M has been studying this new field and she believed it was worth testing. She sent me to the lab for MCAS testing, which includes a 24-hour urine test and blood testing.  The test apparently can't be performed by an ordinary corporate lab, so I had to make a special appointment at my local hospital's lab. Even then, the hospital had to call my doctor's office twice to confirm the procedure, and I had to return the next day to begin the testing.

I received the results last week and they were positive.  Dr. M seemed thrilled because, she said, of the "dozen or so" patients she has sent for MCAS testing, I was the first to receive a positive result.  I felt less thrilled than Dr. M because, based on my limited understanding, the medical profession doesn't know exactly how to treat MCAS other than by trial an error with many, many kinds of histamine blockers and other mast cell inhibitors.  A positive test is like knowing you have an allergy to something, but not knowing what the trigger (allergen) is or how to treat it. (This is just an analogy, I'm not saying MCAS is an allergy.)

Here are the results, starting first with the negative results then moving to the positive.

Negative:

Tryptase Level                    Normals: <11.5 ng/ML     Mine: 2.4
Chromogranin A                 Normals: <93    ng/ML     Mine: 62
Basophils %                        Normals: 0-12   %            Mine: 6.3
Histamine Plasma               Normals: 0-1.0 ng/ML      Mine: 0.96
2,3 Dinor 11B
   Prostraglandin F2A  Normals: <5205 pg/mg    Mine: 2617
2,3 Dinor 11B
   Prostraglandin F2A  (ur)   Normals: <5205 pg/mg    Mine: 2478
N-Methylhistamine, Urine   Normals: 30-200 mcg/g    Mine: 125
N-Methylhistamine, Urine   Normals: 30-200 mcg/g    Mine: 122

Positive:

Leukotrine E4 (urine)        Normals:  <=104 pg/mg    Mine:  158
Leukotrine E4 (urine)        Normals:  <=104 pg/mg    Mine:  221
Postaglandin D2                Normals:  35-115 pg/mL    Mine:  193

Unknown - No Reference Range Established:

Postaglandin D2 (urine)                                               Mine:  98

To me, this raises more questions than it answers.  First, I note that all three of the urine test samples were tested twice.  I'm not certain why, but the results were fairly consistent between tests, so I won't worry about it.

More importantly, how significant are these results really?  Would other knowledgeable MCAS doctors say I clearly have MCAS, or are the results equivocal?  The Leukotrine results provide the following notation:

"Leukotrine E(4) (LTE4) >104 is consistent with the diagnosis of systemic mast cell disease, in adults.  The clinical sensitivity of LTE4 is 48% in patients with systemic mastocystosis.  When LTE4 concentrations are combine with other biochemical markers of mast cell activation, N-methyl histamine (NMH) and 2,3-dinor 11-Beta Prostaglandin F(2) Alpha (2,3BPG), the clinical sensitivity increases to 92%. Results should be interpreted  in the context of the patient's clinical condition."

I don't speak laboratory-jargon, but this seems to indicate that the a positive Leukotrine test, by itself, is not very reliable.  I'm not sure what the positive Postaglandin D2 test adds to this analysis.  The results of that test include the disclaimer:

"This test was performed using a kit that as not been cleared or approved by the FDA and is designated as research only.  The analytic performance characteristics of thes test have been determine by [name of lab].  This test is not intended for diagnosis or patient management decisions without confirmation by other medically established means."   

I didn't necessarily feel this way when I started writing this post, but my confidence level in this new diagnosis is shaky at best.  I have to do my own research before I decide whether and how to act on this diagnosis.  I know many of you are far more knowledgeable about MCAS that me.  I'd love to hear your impressions of and reactions to this post.