Nope. Could be any number of things. Hyper or hypo thyroid responds very favorably to Chiropractic. Upper cervical specifically.
The thyroid will be low if the adrenals are burnt out. And if the adrenals are burnt out it's usually a good sign you've got parasites in your liver. The only other thing that burns out adrenals is prolonged stress. Had a bit of that myself with the war stuff.
Stress can be difined as someone elses problems that are laid on you and become a mystery. Acquisition of truth resolves all stress.
Nutritional deficiencies in iodine and the "B" complex don't help either. So it's not always Iodine. Iodine levels can be "normal" and you can still have a low thyroid.