I have recently started on the challenging road of finding a diagnosis for my flushing/diarrhea/dizziness/headaches/tachycardia/palpitations/etc. Some of the Biomarkers came back positive for Carcinoid (NET) but I am still suspicious of MCAS or Mastocytosis. My Chromogranin A was high and my urine 5-HIAA was high, my tryptase was normal, but never checked after an episode. Does anyone else have experience with getting full workup for Carcinoid with no evidence of a tumor, and then finding out that that have a Mast Cell disorder? There are just SO MANY parallels. Thanks!