Hypothyroidism is usually defined as "insufficient thyroid hormone", which is assumed to be reliably determined by the pituitary hormone TSH, as a surrogate for Free T4. Instead the correct definition is "insufficient T3 effect in tissue throughout the body due to inadequate supply of, or response to, thyroid hormone." So it is not just the supply, but also the response to thyroid hormone at the cellular level. Suboptimal TISSUe T3 EFFECT results in hypothyroid symptoms . Free T3 is the biologically active thyroid hormone. Free T3 provides the energy needed by your body, like gasoline for an engine. Yet your doctor, as many others, did not even test your Free T3 on the false assumption that your body always converts T4 to T3 as needed and that your FT4 level being within range, assures adequate TISSUE T3 EFFECT. This is very wrong. I am sure the doctor would also point to your TSH being within range as further evidence that you could not be hypothyroid. That is also very wrong.
TSH has only a very weak correlation with the thyroid hormones, FT4 and FT3, and a negligible correlation with TISSUE T3 EFFECT. FT4 and FT3 individually have only a weak correlation with TISSUE T3 EFFECT. The best way to try and diagnose a person for the possibility of hypothyroidism, is basically the same as done in the distant past, before the test for TSH was invented. Diagnosis should be based on a full medical history, an evaluation for symptoms that are typical of hypothyroidism, and extended testing to support clinical findings. Tests should always include both Free T4 and Free T3, along with initially testing for cortisol and Reverse T3. Also Vitamin D, B12 and ferritin should be tested and supplemented as needed to optimize.
If the patient has multiple signs/symptoms of hypothyroidism and FT4 and FT3 are in the lower part of their too-broad ranges, that is a strong indication of hypothyroidism. Much less frequently excess cortisol, or Reverse T3, can also contribute to hypothyroid symptoms. If hypothyroidism is tentatively diagnosed, then the patient should be given a trial of thyroid medication adequate to raise FT4 and FT3 into the upper half of their ranges. If symptoms ease, then the theory is confirmed and med dosage should be increased as needed to relieve hypo symptoms, without being influenced by resultant TSH levels. Symptom relief should be all important, not just test results.
Your list of symptoms, and relatively low FT4, are a strong indication of hypothyroidism, You were not tested for Free T3, but instead Total T3, which is not nearly as revealing. If your Free T3 is similar in range to your Total T3, that would be further evidence of hypothyroidism. You really should try to also get tested for Free T3 and Reverse T3 from the same blood draw, along with cortisol, Vitamin D, B12 and ferritin. With your symptoms and FT4 result, your "normal " TSH result only provides a clue that you may have central hypothyroidism. With central, there is a dysfunction in the hypothalamus/pituitary system resulting in TSH levels that are too low to adequately stimulate the thyroid gland to produce hormone. Doctors have been taught that central hypothyroidism is rare. It is rare only because it is rarely diagnosed due to the pervasive reliance on TSH as the main diagnostic.
If you choose to go back to the doctor and try to get the additional tests done, I suggest that you also ask if the doctor is willing to diagnose and treat clinically, for symptoms, rather than just based on TSH, and maybe a FT4 test. I would also ask if the doctor is willing to prescribe T3 med if needed. If either answer is no, then you will need to find a good thyroid doctor that will do both.
If you want to confirm anything I have said, I suggest clicking on my name and then scrolling down to my Journal. There, read at least the one page Overview of a paper on Diagnosis and Treatment of Hypothyroidism: a Patient's Perspective.
Somebody else posted these symptoms and they are the same as mine.
Aches and pains
Need excessive sleep
Losing scalp hair
Dry skin (need to use skin moisturizer)