A number of factors can affect TSH levels. These are important because lab values don ... as with any medical test, there are ...

including a TSH test if medically necessary, once you’ve met your deductible. Your doctor must certify the test is medically necessary, and you must go to a Medicare-approved laboratory.

Different combinations of values can mean different things ... use the same lab for every test. On its own, the TSH test can diagnose thyroid disease, albeit with limitations.