Criteria for diagnosis of MCAS based on a consensus report by an international mastocytosis working group36 and the AAAAI mast cell disorder work group report37
| A | Typical signs of severe, recurrent (episodic) systemic MCA (often in form of anaphylaxis or crisis) (definition of systemic: involving at least two organ systems). |
| B | Objective laboratory evidence of MC activation: preferred marker: increase in serum tryptase level (baseline to baseline plus 20%+2 ng/mL) |
| C | Response to therapy with MC-stabilising agents, drugs directed against MC mediator production or drugs blocking mediator release or effects |
All three criteria need to be fulfilled for diagnosis of MCAS.
AAAAI, American Academy of Allergy, Asthma & Immunology; MC, mast cell; MCAS, mast cell activation syndrome.