Hello! Given the typical symptoms, I have recently proposed that ME/CFS is nothing more than a mast cell activation disorder. One of the good things about this, if it is indeed true that ME/CFS is a mast cell disorder, is that mast cell disorders are testable and treatable within the confines of mainstream medicine. Given the similarity in symptoms, I think it is important to add a fifth test to the mix, to rule out carcinoid syndrome. The five test, all available from mainstream labs, are: 5-HIAA (to rule out carcinoid syndrome) N-methylhistamine Tryptase Prostaglandin D2 11-beta-Prostaglandin F2 alpha Happy testing!