TSH measures the amount of the thyroid stimulating hormone(TSH) in your blood. This can tell you if you have hyperthyroidism(too much thyroid hormone) or hypothyroidism(too little thyroid hormone). This test does not show you what is causing the problem.
Total T4(thyroxine) this test checks for the entire amount of thyroxine in your blood, which helps control metabolism and growth.
Free T4(thyroxine) is a hormone produced by your thyroid that flows through your bloodstream independently.
Total T3(triiodothyronine) test is used to help diagnose hyperthyroidism, a condition in which the body makes too much thyroid hormone. This test can also be used to help monitor treatment for a thyroid disease.
Free T3(triiodothyronine) is a hormone produced by your thyroid that flow your bloodstream independently.
Reverse T3 test measures the inactive form of T3(triiodothyronine).