I'm glad to hear that he will go to the doctor.
The test for hashomoto's thyroiditis is the Anti-TPO antibodies (This is a simple blood test)
I was mistaken, in that in my first post to you, I thought the condition might be due to a type of cancer, now that seems less likely (in other words, I don't think this is caused by cancer)
The blood test above is not one that is done at health fairs. They usually check things like CBC, lipids and blood sugar.
Besides checking for Anti-TPO antibodies he should have thyroid studies (blood tests).
The doctor will usually check for many more things, such as liver function, kidney function, and more. These things can rule out many disorders. It is much more thorough than a health fair, although it is nice to know that the things checked for at the health fair were ok.
Please feel free to reply if you have any more questions or concerns.