I have MCAS and there is no test available sadly. I learned to follow Naturopaths Esp Dr Beth OHara and Dr Becky Campbell. I learned, and continue to learn, so much from them. I did see medical doctors but they are ill informed on this as it is principally diet driven. Each person has a different end result but the process these sites can help you establish your diet. I used Becky Campbells Optimal Reset supplement as the necessary ones are overwhelming and she provides a set to take that work for me. Oddly, the only foods that healed me were the Carnivore program as I’m O+ blood, meat eaters! BBBE. Beef Bacon Butter Eggs. 24/7. Totally healed me and then I slowly introduced one item at a time. This is a constant process. Absolutely nothing processed! It’s a new world!!!