In trying to assess a person's thyroid status, the most important consideration should always be symptoms. So please tell us about any symptoms you have.
Next is biochemical testing to compare to findings from the symptoms evaluation. The tests that should be done are Free T4 and Free T3 (not the same as Total T4 and Total T3), TSH , Thyroid Perosidase antibodies (TPO ab) if TSH is high, Thyroglobulin antibodies if TSH is high but TPO ab is within range, arguably Reverse T3, Cortisol, Vitamin D, B12 and ferritin.
By comparison your TSH was high but no TPO ab or TG ab tests and the Free Thyroxine Index and Total T4 are outdated and not very useful compared to Free T4 and Free T3 tests. So I think your doctor is behind the times. Do you think you could get the additional tests done. If you want to confirm the need and have info to give your doctor to help convince that the additional tests are needed, click on my name and then scroll down to my Journal and read at least the one page Overview of a full paper on Diagnosis and Treatment of Hypothyroidism: A Patient's Perspective.
I also meant to add for comparison, the following link to a list of 26 of the most typical hypothyroid symptoms.
High TSH and high free T4:
* Levothyroxine therapy
* Acute non-thyroidal illness
* Drug effects
* TSH-producing tumour
* Thyroid hormone resistance
* Interfering substances
- abnormal T4 binding proteins
- autoantibodies to T4 or TSH
- exposure to mouse monoclonal antibodies
resulting in production of human anti-mouse antibodies (HAMA).
Here is an example of a patient with high TSH and high free T4...
"Thus, the overall results are consistent with a diagnosis of hypothyroidism, with an artifactual elevation in the originally-measured FT4 due to the presence of an unknown interfering substance.
It is noteworthy that this patient has very high titers of thyroglobulin and thyroid peroxidase antibodies, suggesting a diagnosis of Hashimoto’s thyroiditis."=
=Clinical case seminar: unraveling the mystery of abnormal thyroid function tests
Barkan, A. & Koenig, R.J. Clin Diabetes Endocrinol (2015) 1: 14. https://doi.org/10.1186/s40842-015-0010-8
When you say difficulty maintaining weight, do you mean you are gaining weight, or losing weight?
So you have no thyroid gland function anymore. You are taking 137 mcg of Levothyroxine, yet you still have symptoms that are frequently related to hypothyroidism. Red_Star previously told us that a normal thyroid gland produces 100 mcg of T4 and 10 mcg of T3 daily. Since T3 is 3 times as potent as T4 that equates to 130 mcg of T4 ( 100 + 3 times 10 = 130) . The thyroid med dose required to even provide that much thyroid hormone would have to be significantly higher due to losses during absorption of the med. So that indicates inadequacy in your dosage. In addition a recent, excellent scientific paper concluded that: "Hypothyroid
symptom relief was associated with both a T4 dose giving TSH-suppression below the lower reference limit and FT3 elevated further into the upper half of its reference range." Of course symptom relief should be all important for you, not test results, and especially not TSH when taking thyroid med. Although it is a bit unusual to have a TSH like yours when taking thyroid med, I would be far more concerned with getting the additional testing done and thyroid med optimized. Although it will be interesting to see what your TSH does as you get your thyroid med dosage optimized, which is the most important for you. Note that you may need to add a source of T3 to get your Free T3 into the upper half of its range.
Which gets us back to the need for you to get the additional testing done. Can you get your doctor to do the tests for Free T4 and Free T3 (not the same as Total T4 and Total T3), TSH , Reverse T3, Cortisol, Vitamin D, B12 and ferritin?
If your doctor resists doing those tests, explain that hypothyroidism is not just inadequate thyroid hormone, it can also be caused by an inadequate cellular response to thyroid hormone, which can be affected by those. Cortisol should be neither low nor high, Vitamin D should be at least 50 ng/mL, B12 in the upper end of the range, and ferritin should be at least 100.