A conundrum. I will assume you are correct in saying that low thyroid function mimics the symptoms of ME/CFS, so including people with untreated thyroid problems but no ME/CFS into an ME/CFS study would be wrong. (But you know how utterly stupid those Conspiracy to Deny and Conceal (CDC) studies would still be even if they didn't exclude true ME/CFS patients who happen to have low thyroid function.) However, I believe it is harmful (and potentially VERY harmful) for ME/CFS patients to be on thyroid hormones. Again I refer to Paul Cheney's videotaped lectures where he lists T3, Cortef (cortisol), and meds like Provigil and Ritalin as just about the worst things a doctor can give to an ME/CFS patient. And his reasoning makes sense to me. I'm not quite sure what you mean when you say that it is not possible to have a diagnosis of ME/CFS while you have low thyroid function. Again, I think that most of us who have found our way to the Phoenix Rising forums are quite sure that what we are housebound with is ME/CFS, and that most of us have abnormal thyroid function. And probably most of us have found a doctor who has at least enough knowledge to have correctly diagnosed us with ME/CFS.