Diagnostic Tests for Overactive Thyroid (Hyperthyroidism)
Endocrine System Topic Posted by David Mangusan Jr., PTRP
Overactive thyroid, or hyperthyroidism, is a condition in which the thyroid gland produces too much of the hormone thyroid hormone. Overproduction of this hormone may cause a person to become nervous or irritable, have trouble sleeping, experience fatigue or muscle weakness, have rapid and irregular heartbeat, and become intolerant to heat or hot temperatures.
Several diagnostic tests and procedures may be recommended by the doctor to confirm the diagnosis of hyperthyroidism and find its causes.
Thyroid-Stimulating Hormone (TSH) Test
The TSH test is usually the first test performed by the doctor. It is a very sensitive test because it can detect even small amounts of TSH in the blood. The TSH test can be used to detect mild hyperthyroidism.
TSH is a hormone made by the pituitary gland that stimulates the thyroid gland to produce thyroid hormones. As blood levels of thyroid hormone return to normal, the TSH release is stopped. TSH production and release declines when too much thyroid hormones circulate in the blood. I hyperthyroidism, the TSH reading is below normal. Conversely, a reading above normal may mean that a person has hypothyroidism.
While the TSH test can confirm the diagnosis of hyperthyroidism, additional tests may be necessary to find the cause of the condition. Additional tests may include:
T3 and T4 Test. This test can show if T3 or T4—thyroid hormones—or both are elevated in the blood. A higher than normal levels of one or both of these hormones may indicate that a person has hyperthyroidism.
Thyroid-stimulating immunoglobulin (TSI) test. This test, also called a thyroid-stimulating antibody test, measures the level of TSI in your blood. Most people with Graves’ disease have this antibody, but people whose hyperthyroidism is caused by something else do not.
Radioactive iodine uptake test. The radioactive iodine uptake test measures the amount of iodine your thyroid collects from the bloodstream. Measuring the amount of iodine in your thyroid will help your doctor know what is causing your hyperthyroidism. For example, low levels of iodine uptake might be a sign of thyroiditis, whereas high levels could indicate Graves’ disease.
Thyroid scan. A thyroid scan shows how and where iodine is distributed in your thyroid. This information helps your doctor diagnose the cause of your hyperthyroidism by providing images of nodules and other possible thyroid irregularities.
Note: Your healthcare provider can provide you with more information about the tests and procedures for the diagnosis of hyperthyroidism.
See Also:
Page Last Revised: November 27, 2010
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Several diagnostic tests and procedures may be recommended by the doctor to confirm the diagnosis of hyperthyroidism and find its causes.
Thyroid-Stimulating Hormone (TSH) Test
The TSH test is usually the first test performed by the doctor. It is a very sensitive test because it can detect even small amounts of TSH in the blood. The TSH test can be used to detect mild hyperthyroidism.
TSH is a hormone made by the pituitary gland that stimulates the thyroid gland to produce thyroid hormones. As blood levels of thyroid hormone return to normal, the TSH release is stopped. TSH production and release declines when too much thyroid hormones circulate in the blood. I hyperthyroidism, the TSH reading is below normal. Conversely, a reading above normal may mean that a person has hypothyroidism.
While the TSH test can confirm the diagnosis of hyperthyroidism, additional tests may be necessary to find the cause of the condition. Additional tests may include:
T3 and T4 Test. This test can show if T3 or T4—thyroid hormones—or both are elevated in the blood. A higher than normal levels of one or both of these hormones may indicate that a person has hyperthyroidism.
Thyroid-stimulating immunoglobulin (TSI) test. This test, also called a thyroid-stimulating antibody test, measures the level of TSI in your blood. Most people with Graves’ disease have this antibody, but people whose hyperthyroidism is caused by something else do not.
Radioactive iodine uptake test. The radioactive iodine uptake test measures the amount of iodine your thyroid collects from the bloodstream. Measuring the amount of iodine in your thyroid will help your doctor know what is causing your hyperthyroidism. For example, low levels of iodine uptake might be a sign of thyroiditis, whereas high levels could indicate Graves’ disease.
Thyroid scan. A thyroid scan shows how and where iodine is distributed in your thyroid. This information helps your doctor diagnose the cause of your hyperthyroidism by providing images of nodules and other possible thyroid irregularities.
Note: Your healthcare provider can provide you with more information about the tests and procedures for the diagnosis of hyperthyroidism.
See Also:
Hyperthyroidism (Overactive Thyroid)Adapted from the National Endocrine and Metabolic Diseases Information Service (NIH Publication No. 08—5415 April 2008). Accessed: November 27, 2008
Page Last Revised: November 27, 2010
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