About the test
This test measures your TSH, Free T3, Free T4, and thyroid antibodies
The thyroid is a gland that processes hormones that regulate your metabolism. By measuring your levels of the three main thyroid hormones and thyroid peroxidase antibodies, you may be able to determine if you are experiencing thyroid dysfunction.
Thyroid-Stimulating Hormone (TSH)
Thyroid-stimulating hormone, or TSH, is produced by the pituitary gland. It’s responsible for regulating hormones T3 and T4, which are produced by the thyroid gland. TSH is considered the most sensitive marker for thyroid disease and conditions screening.
T3 (triiodothyronine) is a hormone produced by the thyroid gland. Although it is less abundant than T4, T3 is the more active of these two thyroid hormones. When measured together, they help determine the rate at which cells use energy. Levels of T3 fluctuate when individuals have an underactive or overactive thyroid gland. This test measures free T3, the biologically active form of T3.
T4 (thyroxine) is the predominant hormone produced by the thyroid gland. When measured together, T3 and T4 help determine the rate at which cells use energy. Levels of T4 fluctuate when individuals have an underactive or overactive thyroid gland. This test measures free T4, the biologically active form of T4.
Thyroid Peroxidase Antibodies
Thyroid peroxidase, or TPO, antibodies can bind to thyroid enzymes to suppress thyroid function. Elevated TPO antibodies can be indicative of an autoimmune condition. In the case of an underactive thyroid, also referred to as hypothyroidism, the cause may be Hashimoto’s thyroiditis. Hyperthyroidism, or an overactive thyroid, is often caused by Graves’ disease.
Experiencing symptoms of an underactive or hyperactive thyroid?