A couple of things before further discussion. First, do you take your Tirosint in the morning before the blood draw for your thyroid tests? Second, please give me the range on the lab report for FT4. Why wasn't Free T3 done? FT3 is very important and is likely too low due to reduced conversion of T4 to T3 when taking T4 med. Have you been tested for Vitamin D B12 and ferritin?
With regular T4 medication, 4 hours after a daily dose, FT4 levels are 13-36% higher than the 24 hour trough, and FT3 levels are about 8% above trough. I am not sure what the remaining effect would be at the time of a blood draw 9 1/2 hours after taking the med: however, even the ATA/AACE suggest not taking thyroid med the morning of the blood draw for thyroid tests, in order to avoid false high results.
Your FT4 result of
Your FT4 result of 1.5 is well up in the range; however, you need a FT3 test as well. They need to both be taken into account. Even more important than lab tests is how you are feeling. Were you having any symptoms when the doctor erroneously decided to reduce your med dosage based on your TSH level? I say that is wrong because our bodies get a continuous, very low flow of thyroid hormone in the untreated state. When you take a significant dose of thyroid med all at once it spikes FT4, and to a lesser degree FT3, which then suppresses your TSH level for most of the day. So it is the dosing procedure, not the dose itself that causes TSH suppression. I have some very useful info on all this. I will sen a PM. To access, just click on your name and then click on messages.
Further Vitamin D should be at least 50, so yours is okay. B12 is somewhat higher than needed. Ferritin is a storage form of iron that is readily available for use. Ferritin is a precursor to serum iron levels and it needs to be tested also. Ferritin is very important for a hypothyroid patient and should be at least 100.
A good thyroid doctor will treat a hypothyroid patient by raising FT4 and fT3 as needed to relieve hypo symptoms, without going too far and creating hyperthyroid symptoms. Typically this reuires FT4 at mid-range, and fT3 in the upper half of its range and adjusted from there as needed to relieve symptoms. With the info I can give you perhaps you can convince your doctor to change his dosing procedure and get your levels adequate. IF not then you will need to find a good thyroid doctor that will do so.