If your Doctor gives you a diagnosis of sub-clinical hypothyroidism and if it is the autoimmune type, as most hypothyroidism is, a sub-clinical result on thyroid function tests, does not always tell you how severe a disease process is actually going on in your thyroid. "Thyroid Autoimmunity" means your thyroid is being attacked by antibodies that are sent from your immune system, that recognize your normal thyroid tissue, as a foreign invader, such as a virus, allergen or bacteria. This autoimmune process damages the thyroid gland and also causes it inflammation. The antibodies can also serve to block some of the thyroid hormone, so that it doesn't do the job it needs to, even when there is near-ample thyroid hormone available in your body. The fact is that patients have varying symptoms at the early stage of autoimmune hypothyroidism, which is caused by "Hashimoto's thyroiditis" and as mentioned above, it is the most common cause of low functioning thyroid, in many industrialized countries, including the US.
Doctors need to test hypothyroid patients for "thyroid antibodies". The antibodies to test for by blood labs are the "anti-thyroidperoxidase" (TPO) and the "anti-thyroglobulin" (TG). By testing for Hashimoto's thyroiditis, it can reveal to the patient and their Doctor, if the development of hypothyroidism, was caused by thyroid autoimmunity or "thyroid antibodies". If it is confirmed that a patient has autoimmune thyroid disease, this may also confirm the need to start them on thyroid hormone replacement therapy. Even if the cause is not autoimmune in nature, if the patient’s hormone levels were dropping, they will likely still be started on thyroid hormone replacement medication.
The treating Doctor and the patient being treated for hypothyroidism need to be certain that the dose of thyroid hormone used to treat the hypothyroidism, is at the correct level to return the patient’s metabolism to normal and to relieve their hypothyroid symptoms. Many Thyroid Specialists and Endocrinologists are now using more targeted therapy ranges for monitoring thyroid hormone therapy. The "TSH" for example, which is the most commonly used test of thyroid function (elevates with hypothyroidism), will have a hormone therapy target range of between "0.5 and 1.0" (approximate range: 0.5 to 4.0). Most Doctors start with getting the patient's TSH down to 1.0 and then do any further tweaking of the dose up or down from there, based upon the patient's symptoms. Many MDs and GPs are not aware of the more targeted therapy for treatment of hypothyroidism but it is stated in the most reputable medical research publications that are available, including that of the AACE (American Association of Clinical Endocrinologists) and on the MedLinePlus website, created by the National Institutes of Health.
I believe patients should obtain copies of their most recent lab tests that were in follow-up on their thyroid hormone therapy. The U.S. "HIPPA Law" entitles patients to copies of their medical lab tests results. They should see if their TSH has been brought down to close to a 1.0 and if it hasn't been, they should discuss with their Doctor, using this as the target TSH level, to see if it better resolves their symptoms. The way TSH works, is that it goes lower when you’re getting more thyroid hormone and it elevates to a higher number when you're getting less.
Having a more targeted therapeutic TSH range, for treating hypothyroidism and sub-clinical hypothyroidism, results in better improvement for patients.

