**Note: All laboratory testing requires an authorizing physician. DHA Laboratory offers a patient direct program that partners you with an authorizing physician. If you have any additional questions regarding the availability of testing, please contact our laboratory by telephone or email.**
The Thyroid function test is helpful in the evaluation of hypothyroidism or hyperthyroidism, used with thyroxine (T4) or equivalent to provide free T4 index (FTI). An indirect measure of binding protein, the T3 uptake reflects available binding sites (ie, reflects TBG). T3 uptake is not a measurement of serum T3. It should never be used alone; rather, its usual application is use with thyroxine (T4).
Thyroxine (T4) Free tests are used to help evaluate thyroid function and diagnose thyroid diseases, including hyperthyroidism and hypothyroidism. Test is usually ordered after discovering that the thyroid stimulating hormone (TSH) level is abnormal.
Tri-iodothyronine (T3) Total test is used to evaluate thyriod functions and to help diagnose hyperthyroidism. The Total T3 can be affected by protein levels and protein binding ability, but the free T3 is not.
Thyroid peroxidase (TPO) is an enzyme normally found in the thyroid gland and plays an important role in the production of thyroid hormones. A Thyroid peroxidase (TPO) test detects antibodies against TPO in the blood.
Thyroglobulin Ab is used to check blood levels of antibodies the body has made against thyroglobulin, indicating autoimmune thyroiditis, or Hashimoto thyroiditis.
Thyroxine-Binding Globulin (TBG) is produced in the liver and is a circulating protein that reversibly binds thyroid hormones, (T3) and (T4) and carries them in the bloodstream. A Thyroxine-Binding Globulin (TBG) test measures the protein in the blood and can be useful for evaluating thyroid function.
A Tri-iodothyronine (T3) Free test is used to evaluate thyroid functions and to help diagnose hyperthyroidism. The T3 test is usually ordered following an abnormal TSH and T4 test.
Reverse Tri-iodothyronine (RT3) is a biologically inactive form of T3. Normally, when the liver converts T4 to T3, it also produces a certain percentage of RT3. A Reverse T3 test is used to evaluate thyroid functions and hyperthyroidism.