I believe i have a problem with an underactive thyroid. what kind of doctor should i see that would give me a more extensive examination?

GP, endocrinologist: Diagnosing hypothyroidism is not difficult despite what you may read on the internet. The most sensitive test is a TSH level. When high, it implies that the thyroid level is low. One then checks a free T4 level. Although some alternative doctors will claim that a TSH above 2 is abnormal, the vast majority of people with low thyroid will not have symptoms until the free T4 level is low.