Tryptase? I check it, sure. But I can’t say I care when it’s negative. Tryptase is elevated in only a minority of those with mast cell activation. That’s why the new Consensus-2 guidelines updated the diagnostic framework for MCAS — and finally gave us the flexibility to treat the patient, not just the numbers. Consensus-2 Criteria for MCAS: 1. Typical symptoms of mast cell activation (affecting ≥2 systems — e.g., flushing, GI upset, tachycardia, brain fog) 2. Elevated mast cell mediators (e.g.,

Let’s talk about MCAS — Mast Cell Activation Syndrome. The tests we have? Honestly… not that helpful. Most have low sensitivity — meaning they can miss the diagnosis even when it’s really there. Serum tryptase? Often normal in MCAS. Urine prostaglandins, leukotrienes? Only elevated if you test right after a flare and the sample is handled perfectly. Real-world sensitivity? Likely under 50%. Here’s the key: one of the diagnostic criteria for MCAS is improvement with therapy. So if your symptoms i