Do you take levothyroxine with one full glass of water on an empty stomach and wait an hour before eating - food interferes with the uptake of thyroid hormones.
Do you have the earliest possible blood tests, fasting and allow a 24 hour gap between your last dose of levo and the test and take it afterwards?
Drop a note to your endocrinologist and say that he disbelieves that you have been taking thyroid hormones daily that you have been given advice by the NHS Choices for information/advice on dysfunctions of the thyroid gland and have been notified that as your FT4 and FT3 are at the bottom of the range, rather than towards the top, that is why the TSH is at the higher end of the range, which suggests that, due to the high TSH and low FT3 and FT4 that you may not able to convert levothyroxine of 175mcg to sufficient T3. As levothyroxine (T4) is an inactive hormone and has to convert to T3, it may be that your body is not capable of doing so. Especially if you have a defective gene which means you cannot convert.
Tick off your clinical symptoms:
This is an extract from the following link:-
Some people do not convert their thyroxine adequately into T3. This could be due to lack of certain vitamins and minerals or possibly due to a faulty gene. The DIO2 gene was researched in 2009 and the results were published in the paper entitled, "Common Variation in the DIO2 Gene Predicts Baseline Psychological Well-Being and Response to Combination Thyroxine Plus Triiodothyronine Therapy in Hypothyroid Patients" by V Panicker, P Saravanan, B Vaidya, J Evans, A Hattersley, T Frayling & C Dayan - jcem.endojournals.org/content/94/5/1623.full.pdf+html
The researchers found that patients on levothyroxine (T4) alone felt worse if the faulty DIO2 gene was inherited through one parent and worse still if they inherited the faulty gene from both parents.
The patients on this study were given T4 only for a set period and then combination treatment of both T4 and T3. The patients who had normal genes did not feel any different on combination treatment. However, those who had one faulty gene felt better on the combination treatment and those with both faulty genes felt better still.
This means that there is a possibility that patients who are on levothyroxine alone and still have symptoms may improve with the addition of T3.
Because this faulty gene causes a deficiency of T3 within the cells, the usual thyroid hormone function tests will not show up a problem. This means that your TSH, FT4 and FT3 blood tests will look normal.
The researchers concluded, “Our results require replication but suggest that commonly inherited variation in the DIO2 gene is associated both with impaired baseline psychological well-being on T4 and enhanced response to combination T4/T3 therapy, but did not affect serum thyroid hormone levels.” This means that some people do not convert but this doesn’t show in their blood tests.