Fact of the day: Thyroid-Stimulating Hormone (TSH) - A thyroid-stimulating hormone (TSH) blood test is used to check for thyroid gland problems. TSH is produced when the hypothalamus releases a substance called thyrotropin-releasing hormone (TRH). TRH then triggers the pituitary gland to release TSH. TSH causes the thyroid gland to make two hormones: triiodothyronine (T3) and thyroxine (T4). T3 and T4 help control your bodys metabolism. Triiodothyronine (T3) and thyroxine (T4) are needed for normal growth of the brain, especially during the first 3 years of life. A baby whose thyroid gland does not make enough thyroid hormone (congenital hypothyroidism) may, in severe cases, be mentally challenged. Older children also need thyroid hormones to grow and develop normally. This test may be done at the same time as tests to measure T3 and T4. A test for thyroid-stimulating hormone (TSH) is done to: Find out whether the thyroid gland is working properly. An underactive thyroid gland (hypothyroidism) can cause symptoms such as weight gain, tiredness, dry skin, constipation, a feeling of being too cold, or frequent menstrual periods. An overactive thyroid (hyperthyroidism) can cause symptoms such as weight loss, rapid heart rate, nervousness, diarrhea, a feeling of being too hot, or irregular menstrual periods. Find the cause of an underactive thyroid gland (hypothyroidism). TSH levels can help determine whether hypothyroidism is due to a damaged thyroid gland or some other cause (such as a problem with the pituitary gland or the hypothalamus). Keep track of treatment with thyroid replacement medicine for people who have hypothyroidism. Keep track of thyroid gland function in people who are being treated for hyperthyroidism. This treatment may include antithyroid medicine, surgery, or radiation therapy. Double-check the diagnosis of an underactive thyroid gland in a newborn (congenital hypothyroidism). How To Prepare Tell your doctor if you have had any tests in which you were given radioactive materials or had X-rays that used iodine dye within the last 4 to 6 weeks. Your test results may not be correct if you have had iodine contrast material before having a thyroid-stimulating hormone (TSH) test. High TSH levels may be caused by: An underactive thyroid (hypothyroidism). Hashimotos thyroiditis is the most common cause of primary hypothyroidism. A pituitary gland tumor that is making too much TSH. This is uncommon. Not taking enough thyroid hormone medicine for treatment of an underactive thyroid gland. Low TSH levels may be caused by: An overactive thyroid gland (hyperthyroidism). Causes of hyperthyroidism include Graves disease, a type of goiter (toxic multinodular goiter), or a noncancerous (benign) tumor called a toxic nodule. Damage to the pituitary gland that prevents it from making TSH (a condition called secondary hypothyroidism). Taking too much thyroid medicine for treatment of an underactive thyroid gland. Pregnancy during the first trimester. Reasons you may not be able to have the test or why the results may not be helpful include: Taking medicine, such as corticosteroids, levodopa, heparin, dopamine, lithium (such as Carbolith or Duralith), methimazole (Tapazole), and propylthiouracil. Having had a recent X-ray with iodine dye or test using radioactive materials. Having severe stress or a long-term (chronic) illness. Source: webmd/a-to-z-guides/thyroid-stimulating-hormone-tsh
Posted on: Mon, 28 Oct 2013 11:04:23 +0000
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