Description
TSH stands for thyroid stimulating hormone. A TSH test is a blood test that measures this hormone. The thyroid is a small, butterfly-shaped gland located near your throat and the hormone made by it regulates the way your body uses energy.TSH is produced by the pituitary gland in your brain. This gland tells your thyroid to make and release the thyroid hormones into your blood.A TSH test is done to find out if your thyroid gland is working the way it should. Either it is overactive (hyperthyroidism) or underactive (hypothyroidism).
The test can also detect a thyroid disorder before you have any symptoms. If untreated, a thyroid disorder can cause health problems. This test can be performed at any time during the day. No preparation is needed (such as overnight fasting)and just require a small prick from the needle in your arm . The Thyroid Profile with TSH measures thyroid function, which regulates your metabolism and your body`s ""thermostat"". Significant deviations from the normal range may require further evaluation by your physician.
For differential diagnosis of primary, secondary, and tertiary hypothyroidism. Also useful in screening for hyperthyroidism. This assay allows adjustment of exogenous thyroxine dosage in hypothyroid patients and in patients on suppressive thyroxine therapy for thyroid neoplasia. The TSH test monitors thyroid function and diagnoses thyroid disorders, such as hyperthyroidism and hypothyroidism. A significant deviation from the normal range may require further evaluation by your physician.
The T3, Free test measures serum triiodothyronine (T3) not bound to thyroid hormone-binding proteins (thyroid hormone-binding globulin [TBG], transthyretin, albumin). It is used, primarily in concert with measurement of thyroid-stimulating hormone (TSH, test code 899) and free T4 (FT4, test code 866), in the diagnosis and management of hyperthyroidism and to clarify thyroid hormone status in the presence of a possible thyroid hormone-binding protein abnormality.
The FT3 (or total T3) test is usually ordered following an abnormally low TSH result and/or a clinical picture suggestive of hyperthyroidism, particularly if the free T4 test result is not elevated. Up to 10% of patients with proven hyperthyroidism (due to Graves disease or an autonomously secreting thyroid nodule) may have an elevated FT3 but normal FT4 (T3 toxicosis), particularly early in the course of disease or as an early sign of relapse after treatment. In contrast, there is limited utility for FT3 testing for suspected hypothyroidism as FT3 levels may not drop until well after both TSH and FT4 rise.
T3 (triiodothyronine) is one of the main hormones produced by the thyroid. Along with T4, T3 is responsible for regulating metabolism, heart rate, body temperature, mood, mental alertness and more.T3 and T4 can either bind to proteins, or they can float freely in the blood. When T3 floats freely, it is considered free T3.When the body doesn’t produce enough T3 and T4 hormones, it can cause hypothyroidism.If free T3 is too high, it may indicate an overactive thyroid. An overactive thyroid is referred to as hyperthyroidism.You should test your free T3 in order to get a more thorough understanding of your thyroid’s functioning and/or monitor an ongoing thyroid issue. Keep in mind that measurements from free T3 alone cannot detect a thyroid issue.
The T4 Free (FT4) test measures serum thyroxine (T4) that is not bound to thyroid hormone-binding proteins (thyroid hormone-binding globulin [TBG], transthyretin, albumin) and is thus readily available to target cells. This test is used with thyroid-stimulating hormone measurement (TSH, test code 899) in the diagnosis of hyperthyroidism (usually displaying elevated FT4) and hypothyroidism (low FT4), including congenital and acquired hypothyroidism.
The FT4 test is used to assess thyroid function, monitor thyroid conditions, and assess treatment effectiveness. It has largely replaced the total T4 test (test code 867), which measures both bound and free T4, because the FT4 test is less affected by levels of thyroid hormone-binding proteins.
This test uses a T4 analog, rather than equilibrium dialysis, to determine the amount of free T4. It therefore differs from the T4 Free, Direct Dialysis test (test code 35167). In the general population, the analog FT4 test is most useful as a follow-up test when TSH results are abnormal.
It may also be used instead of TSH testing to assess thyroid function in patients with
(1) known pituitary abnormalities;
(2) chronically suppressed TSH, as often seen in patients for months after successful treatment for Graves disease ; or
(3) a need to assess thyroid hormone dose changes sooner than the 6-8 weeks required for TSH to reach a new stable level.
When the levels of thyroid hormone-binding proteins are very abnormal (eg. congenital TBG deficiency or excess; preterm infants ) or the affinity of binding proteins is altered (eg. familial dysalbuminemic hyperthyroxinemia), the T4 Free, Direct Dialysis test will provide more accurate results.
The Free T4 test is used to assess thyroid function, indicate hypothyroidism or hyperthyroidism, help diagnose thyroid disease, and evaluate the effectiveness of thyroid treatment.Thyroxine exists in two forms: bound and free. Bound thyroxine attaches to proteins. Free thyroxine (FT4) is the active form of thyroxine and is not bound to proteins in the blood, which allows it to travel into organs that use T4. Fluctuations in protein levels do not affect free T4, so free T4 is a more reliable measurement of T4 levels in the blood.
By seeing if you are in the normal range, the free T4 test can help detect if there is too much (hyperthyroidism) or too little thyroxine (hypothyroidism), aid in the diagnosis of pituitary disorders and female infertility, and monitor thyroid hormone treatment.
