I'm not saying that most cases of CFS are hypothyroid, but I do think that since CFS is a diagnosis given when other abnormalities are "excluded", I think it's very much worth the time, money and effort to take a good look at your TSH, and even better get a look at your ft3,ft4 and thyroid antibodies.
There is much debate about narrowing down the TSH range to 0.5-3.0, but studies such as
show that even 3.0 is too high. Max should be somehwere around 2.0 and optimal somewhere between 0.5 and 1.
However your local doctor or endoctrinologist might not know about this.
The good news is that if a lot of you are hypothyroid and that is the problem, there is an effective and cheap treatment.
www.stopthethyroidmadness.com is a good rescource on what a proper treatment should consist of. The gall leading the site tends to favour armour, natural descicated thyroid containing t4, t4, t3, t1 and calcotonin and not just t4 like synthetic synthroid.. She also stresses that fact that if adrenal fatigue is present it should be treated before or in conjunction with thyroid treatment.