What else could it be?
...a lot of things! This is one reason why investigating other potential cause for a patient's symptoms is so important. Maybe you're not dealing with a zebra, after all. Maybe you're dealing with a hippopotamus!
As you might expect from the nebulous, multi-system symptoms experienced by many mast cell patients, there are instances in which some patients are "diagnosed" without due diligence and later discover that other conditions were in fact responsible for their symptoms. On resolution of these symptoms, they ask if MCAD still belongs on their chart.
Conditions which may MIMIC a mast cell disorder (a very incomplete list)
It's important to remember that many of these conditions may also trigger worsening of a mast cell disorder or present comorbidly with a mast cell disorder. However, if addressing one or more of these conditions resolved your symptoms and you do/did not require mast cell treatment, it is extremely unlikely that your symptoms arose as a result of a mast cell disorder, instead.
Thyroid issues of various kinds
Mycotoxin or mold illness
Recurrent EBV (mononucleosis)
Various cardiac conditions
Various neurological conditions
Various hepatic conditions
Various other systemic inflammatory conditions
Again, many of these conditions may be comorbid with or even trigger a clinical mast cell disorder (or, in the case of those like NET's, carcinoid, spontaneous implant rejections, and various cancers or other inflammatory conditions, arise in whole or in part as a result of MCAD); it's if treating one of these rather than a mast cell disorder is what resolved your symptoms that you should reconsider MCAD as a viable cause of these symptoms.
Likewise, if one of these these therapies resolved your symptoms in the absence of concurrent mast cell treatment, it is extremely unlikely that these symptoms resulted from a mast cell disorder (an incomplete list):
Beta antagonists (drugs like propranolol)
Other antibiotics on their own
Various herbs usually targeting one of the above conditions
Withdrawal from a medication (withdrawal symptoms of some medications may mimic mast cell symptoms)
IV vitamin therapy
Most other IV supplements that are not listed under “treatment”
A juice or other cleanse
Longer term fasting
Cleansing or “detox” diets
Avoidance of your allergens
Allergy shots or other allergen therapies
Miracle mineral solution (chlorine)
Colonics (any kind)
Blood type diets and other cures
Ingesting binders like charcoal or clays
Note that just the tolerance of some of these therapies also strongly tip the scales against the likelihood that the patient could have been suffering from a concurrent mast cell disorder at the time.
So, for those patients who were not able to rule out other causes for their symptoms, how might they and their practitioners know if a mast cell disorder was in fact causing their symptoms after their resolution? (When do you put "currently invisible mast cell disorder" on the chart?)
Usually, the correct answer is the most simple: If mast cell treatment (and almost universally, the avoidance of the patient's current triggers), is what resolved/controls the patient's symptoms, a mast cell disorder is almost certainly responsible for these symptoms (and this should stay on the chart for future needs). If treating some unrelated condition accomplishes this, that other condition is almost certainly responsible for the patient's symptoms (and that's what should stay on their chart in case of a recurrence or a need for continued treatment.)
Many mast cell patients are able to decrease one or more elements of their treatment plans after long term use as their condition becomes more stable, but most still require long term medical management. Improvements in the patient's baseline should of course be celebrated, but they should not be a surprise when they occur. That's something treatment should do; if treatment does not even begin to resolve symptoms, if a mast cell patient's condition doesn't improve at all with appropriate treatment, there's probably at least some other condition at play.