Re: Question about too much radiation
Yes, too much radiation can affect your thyroid, but it's not usually from a series of x-rays, it's usually from radiation treatments for cancers (ie, radiation for breast cancer) or exposure to a nuclear plant disaster, or working with radiation for many years---that type of thing.
It also probably wouldn't happen immediately---many people exposed to the Chernobyl nuclear plant disaster, which was in 1986, are coming out with thyroid cancers now.
Perhaps the doctor was trying to say, don't expose yourself to all those tests and x rays unless there is a very valid reason? (I'm not sure, but I think MRI's don't use radiation by the way)---I don't think they can see radiation in your blood, so the doctor could have been making the general statement.
People can have great sensitivities to these things, but you could have had a progressive thyroid disease that is coincidentally now showing up in your blood work.