If you didn't follow the procedure below, ask for new tests to be done. If he is reluctant say you have become a member of Healthunlocked Thyroiduk.org.uk the NHS Choices for advice.
You must get the earliest appointment, fasting (you can drink water) and allow a gap of 24 hours between last dose and the test and take afterwards.
Ask GP for a Full Thyroid Function Test i.e. TSH, T4, T3, Free T4, Free T3 and thyroid antibodies. Antibodies are important because if these are present we have an Autoimmune Thyroid Disease called Hashimotos but treatment is the same for hypthyroidism.
Also ask for B12, Vit D, iron, ferritin and folate as we are usually deficient.
If you have no Thyroid Gland at all I think you should have a combination of T4/T3 and Research Teams have shown that most recover (even those who still have a gland) with a combination dose, if optimal.
These are two excerpts from the following link:-
1, Medical boards/councils often discipline clinicians who do not follow the treatment
standards. When clinicians run afoul of custom and medical practice guidelines, they invite investigation, fines, and loss of license.
2. Dose Selection in T3/T4 Study RCTs The second logical basis for a conclusion
is the actions taken, i.e., the doses given to the subjects. Most subjects received T3 below its
adult starting dose of 25 mcg/day.
The subjects in RCTs received T3 in some ratio to the withdrawn T4. The various RCTs used T4:T3 ratios of 14:1, 10:1, and 5:1. Subsequent research by the US National Institutes of Health (NIH) found the therapeutic equivalence was 3:1.
Thus, most of the subjects were under treated with the T3/T4 combination. In light
of the NIH finding, the conclusion that T3 therapy is never needed is invalid.
When you take thyroid hormones it should be taken on an empty stomach and most take it when they get up with one full glass of water and wait about an hour before eating. Some take it at bedtime as long as they've last eaten 3 hours before. Food interferes with the uptake.
Always get a print-out with the ranges every time you have a test for thyroid hormones.
If GP or lab doesn't do the Free T4 and FT3 we have recommended labs which do home pin-prick tests..