When I diagnose Mast Cell Activation Syndrome (MCAS), I use the Consensus 2 criteria. This method moves beyond the traditional tryptase-level criteria of Consensus 1, and focuses instead on symptom charts, response to treatment and specific lab tests. I’ve found this method to work impeccably. Many practitioners are not aware of mast cell activation syndrome and the complexity of how it can present, or either continue to use the outdated Consensus 1 approach or, worse, revert to an understanding