The reason why a doctor or endocrinologist may tell you free T3 and thyroglobulin antibodies are unnecessary...
Excerpt from the About website "2012 Hypothyroidism Guidelines Published"...
"The American Association of Clinical Endocrinologists (AACE) and the American Thyroid Association (ATA) convened a task force on hypothyroidism in adults. The result was jointly published in 2012 in the journals Thyroid and Endocrine Practice as Clinical Practice Guidelines for Hypothyroidism in Adults (The "Guidelines.")
The Guidelines present "evidence-based recommendations" that, according to the report, "were developed to aid in the care of patients with hypothyroidism and to share what the authors believe is current, rational and optimal medical practice for the diagnosis and care of hypothyroidism."
(Note: For the purposes of their guidelines, the task force defined overt hypothyroidism as a Thyroid Stimulating Hormone (TSH) level above 10 mIU/L, and subclinical hypothyroidism as a TSH less than 10 mIU/L, with lower Free Thyroxine (Free T4) levels.)
The following are highlights of some of the Guidelines' key recommendations. The full list of guidelines can be read online at in the journal Thyroid.
Diagnosis-Related Guidelines
The Guidelines include a number of recommendations related to the diagnosis of hypothyroidism. The most notable include the following.
Thyroid peroxidase antibody (TPOAb) measurements -- which when elevated, can confirm Hashimoto's thyroiditis -- should be considered when evaluating patients with subclinical hypothyroidism.
When a patient has thyroid nodules, and autoimmune thyroiditis is suspected, measuring TPOAb should be considered.
Measurement of total triiodothyronine (T3) or Free T3 should not be used to diagnose hypothyroidism."
***
Excerpt from Medscape - Antithyroglobulin:
"One study examined 2030 consecutive patients who had both antimicrosomal and antithyroglobulin antibodies to determine if they had Hashimoto thyroiditis. Positive results for antimicrosomal antibodies were obtained in 99% of all patients, but only 36% of patients were positive for antithyroglobulin. These results suggest that performing both tests is costlier and does not offer any diagnostic advantage. Therefore, thyroglobulin antibody testing is not recommended for the diagnosis of Hashimoto thyroiditis.[4]"
Nordyke RA, Gilbert FI Jr, Miyamoto LA, Fleury KA. The superiority of antimicrosomal over antithyroglobulin antibodies for detecting Hashimoto's thyroiditis. Arch Intern Med. Apr 12 1993;153(7):862-5. [Medline].
Seconding Gimel, run away! I know it isn't trivial to switch doctors, but this one doesn't have the knowledge or the respect for you that he should have for you to get good care.
Run, don't walk away from that doctor. He doesn't really know much about testing and treating thyroid patients and seems too arrogant to consider any other way. Guess he nevefr heard of secondary and tertiary hypothyroidism, with which the TSH will be low, along with somewhat low Free T4 and free T3.
You don't necessarily need another Endo. Endos are frequently like your doctor and have the "Immaculate TSH belief" and mistakenly think that TSH tells them all they need to know about thyroid status. Others will test beyond TSH, but usually only Free T4 and then use "Reference range Endocrinology", by which they will tell you that a thyroid test result that falls anywhere within the so-called "normal" range is adequate. That is also very wrong.
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."
http://hormonerestoration.com/files/ThyroidPMD.pdf
So, please tell us about your symptoms that may relate to being hypothyroid. Also, have you been tested for Vitamin D, B12, and ferritin? If so, please post those results and ranges as well.