Why Does MCAS Not Respond to Standard Treatment? The Four Mechanistically Distinct Patterns — Frequently asked questions about treatment-resistant MCAS

How do I know which pattern I have? The recognition questions in the article above are a starting point. Reactions dominantly tied to food suggest Pattern A. Reactions tied to autonomic state, posture, and sleep suggest Pattern B. Reactions tied to specific locations and environmental exposures suggest Pattern C. Persistent symptoms with elevated baseline tryptase suggest Pattern D. Most cases have features of more than one pattern, and identifying the dominant pattern is a clinical task that benefits from a structured case review. Can I have more than one pattern at the same time? Yes. The most common combination in my case experience is Pattern A and Pattern B together, where post-infectious or post-antibiotic barrier failure has both produced the gut driver and degraded the autonomic regulation. The treatment approach in these cases addresses both, usually starting with whichever is producing the most acute symptom burden. Why does cromolyn help me but not enough? The most common reason is that cromolyn is suppressing the mast cell response while the upstream driver continues to signal. This is most often Pattern A (the cromolyn helps mucosal cells but the barrier keeps signaling) or Pattern C (the cromolyn helps but the exposure continues). Identifying the upstream driver and addressing it is what produces the durable response. Is the four-pattern framework recognized by ma