Take it from me, some people need their TSH near 0 to feel well. It just goes to show how unreliable a measure of thyroid health the TSH is. Actually, Free T3 is usually the best indicator of health, but even just symptoms should be able to tell you whether or not you feel right. Stress to your doctor how good you feel, and that you have not had any hyper symptoms but feel that all your hypo symptoms have dissipated. Consider sharing this study with your doctor as well:
"It is theoretically possible that patients receiving exogenous L-thyroxine for primary hypothyroidism should have suppressed TSH levels if physiological needs are constantly met."
I agree with ahmee. Also, patients don't go to doctors complaining about their TSH level. They go to the doctor because of symptoms. Doctors like to think that TSH accurately reflects levels of the actual thyroid hormones; however, TSH cannot be shown to correlate well with either Free T3 or Free T3, much less with symptoms, which should be the most important consideration.
When a patient is already taking thyroid meds, TSH is frequently suppressed below the range, in order to achieve euthyroidism. My TSH has been around .05 or less for well over 25 years, without hyper symptoms. In fact I continued having lingering hypo symptoms until learning from this forum, about the importance of Free T3.
In addition to the quote from ahmee above, from this link you can see that this scientific study concluded that none of the usual thyroid tests are adequate for medicating a hypothyroid patient.
"Measurements of serum concentrations of total thyroxine, analogue free thyroxine, total triiodothyronine, analogue free triiodothyronine, and thyroid stimulating hormone, made with a sensitive immunoradiometric assay, did not, except in patients with gross abnormalities, distinguish euthyroid patients from those who were receiving inadequate or excessive replacement. These measurements are therefore of little, if any, value in monitoring patients receiving thyroxine replacement."
So, if TSH is useless as a diagnostic by which to medicate a hypothyroid patient, and the other typical thyroid tests are also inadequate, how should a hypo patient be treated? The answer is that a good thyroid doctor will treat a hypo patient clinically by testing and adjusting Free T3 and Free T4 as necessary to relieve symptoms, without being constrained by resultant TSH levels. You can get some good insight into clinical treatment from this letter written by a good thyroid doctor for patients that he sometimes consults with after initial tests and evaluation. The letter is then sent to the participating doctor of the patient to help guide treatment. In the letter, please note the statement, "the ultimate criterion for dose adjustment must always be the clinical response of the patient."
TSH is a pituitary hormone and is not a good indicator of thyroid hormone levels. Many of us on thyroid replacement have TSH levels that are low or suppressed. My own TSH lives at < 0.01; hasn't come up in 5 years, no matter how much my med is lowered, yet my FT3/FT4 are sometimes lower than they need to be to alleviate symptoms.
TSH neither causes, nor alleviates symptoms, and once on medication, it often becomes totally irrelevant.
We do understand that in UK, doctors are closely bound by the guidelines of NHS, which centers around TSH, so members are less likely to get adequate treatment.
It's important to note that fibromyalgia is a set of unexplained symptoms that often go away with thyroid hormone treatment. You've seen this yourself, with your symptoms getting better, so you may actually need an increase in medication, not a decrease, in order to alleviate the rest of your symptoms.
What was the reference range for the FT4? Ranges vary lab to lab and have to be posted with results. Is there any chance you might get your doctor to test FT3? FT3 is the hormone that's actually used by the individual cells, and sometimes we don't adequately convert FT4 to FT3 and have to add a source of T3. Again, we understand that T3 treatment is not part of the NHS guidelines and is very hard to get in UK.