The results of a thyroid function test help medical professionals assess thyroid function or determine the underlying cause of a thyroid disorder, states the National Endocrine and Metabolic Diseases Information Service. Thyroid hormones have an effect on breathing, brain development, metabolism, menstrual cycles and muscle strength.Continue Reading
The TSH, T3, T4, TSI and TPOab tests are used to assess thyroid function, according to the National Endocrine and Metabolic Diseases Information Service. TSI stands for thyroid-stimulating immunoglobulin, while TPOab stands for thyroid peroxidase antibody. The TSH test measures the amount of thyroid-stimulating hormone secreted by the pituitary gland. Too much TSH is indicative of hypothyroidism, while too little TSH is linked to hyperthyroidism. The T3 and T4 tests are also useful for diagnosing hypothyroidism and hyperthyroidism.
TSI is an auto-antibody that stimulates the thyroid cells to secrete excess thyroid hormone, reports the National Endocrine and Metabolic Diseases Information Service. The TSI test checks to see if a person has these auto-antibodies circulating in his blood. Anti-TPO antibodies attack thyroperoxidase, an enzyme found in the thyroid cells. The antithyroid antibody test looks for these antibodies in a patient's blood sample. This test is used to diagnose Hashimoto's disease.
Hypothyroidism occurs when tissues do not respond as well to thyroid hormones as they should, reports the Cleveland Clinic Center for Continuing Education. In contrast, hyperthyroidism develops due to the effects of excess thyroid hormones on body tissues. Thyroid function tests help determine the underlying cause or causes of hypothyroidism and hyperthyroidism.Learn more about Medical Ranges & Levels