Description
Also known as: Thyrotropin.
TSH is produced by the pituitary gland. It stimulates the production and release of T4 and T3 by the thyroid gland.
When TSH concentrations are high, the thyroid will make and release excessive amounts of T4 and T3 and the patient may experience hyperthyroidism, with symptoms such as rapid heart rate, weight loss, nervousness, hand tremors, irritated eyes, and difficulty sleeping.
With decreased production of thyroid hormones (hypothyroidism), the patient can experience symptoms such as weight gain, dry skin, constipation, cold intolerance, and fatigue.
Its concentration is measured by means of analysis of a blood sample drawn from the vein in the arm.
Purpose of the test
To meassure the level of TSH in blood in order to diagnose thyroid disorders and to monitor treatment of hypothyroidism and hyperthyroidism.
The TSH test is often chosen for evaluating thyroid function and/or symptoms of hyper- or hypothyroidism.
TSH testing helps in :
• diagnose a thyroid disorder in a person with symptoms
• screen newborns for an underactive thyroid
• monitor thyroid replacement therapy in people with hypothyroidism
• diagnose and monitor female infertility problems
• help evaluate the function of the pituitary gland
• screen adults for thyroid disorders
Reference range values
0.40 - 4.00 mU/L
Abnormal findings
If after a TSH test result high and a T4 test result normal, a T3 test result is normal, it can indicate a mild form of hypothyroidism.
If after a TSH test result high and a T4 test result low, a T3 test result is normal or low, it can indicate hypothyroidism.
If after a TSH test result low and a T4 test result normal, a T3 test result is normal, it can indicate a mild form of hyperthyroidism.
If after a TSH test result low and a T4 test result normal or high, a T3 test result is normal or high, it can indicate hyperthyroidism.
If after a TSH test result low and a T4 test result normal or low, a T3 test result is normal or low, it can indicate a nonthyroidal illness, for example a rare pituitary hypothyroidism.