Thyroid Panel with Thyroid-Stimulating Hormone (TSH) – Thyroid function is crtical to your metabolism and affects your energy level, heart rate, weight control, and more. The thyroid-stimulating hormone is produced in the pituitary gland and stimulates the production of thyroid hormones. The TSH helps identify an underactive or overactive thyroid state. This comprehensive evaluation of your thyroid hormone levels includes: T-3 Uptake, T4, Free Thyroxine Index (T7), and Thyroid-Stimulating Hormone (TSH).
Free T3: Test for evaluating thyroid function and assessing abnormal binding protein disorders.
Free T4: Free T4 may be indicated when binding globulin (TBG) problems are perceived, or when conventional test results appear to be inconsistent with clinical observations. It is normal in those with high thyroxine-binding globulin hormone binding who are euthyroid (i.e., free thyroxin should be normal in nonthyroidal diseases). It should also be normal in familial dysalbuminemic hyperthyroxinemia.
Reverse T3: Also known as RT3 or REVT3, is a biologically inactive form of T3, or triiodothyronine, one of two major hormones produced by the thyroid (the other is T4, or thyroxine). Under normal conditions, the body converts T4 to T3 and RT3 in specific ratios. In certain circumstances, the amount converted to RT3 rises, such as when the body is under stress, as in cases of serious or acute illness or injury. Drugs such as amiodarone and glucocorticoids can also cause increased RT3 levels. RT3 levels alone may not be indicative of a thyroid condition, since stress can cause levels to rise. A more accurate assessment may be gained by combining the Reverse T3 Test with the Free T3 Test to evaluate the ratio between RT3 and free T3 levels.