hormonal and metabolic disorders
Overview of the Thyroid Gland
Diagnostic Tests of the Thyroid Gland
Doctors first examine the person and feel the person's neck to see whether the thyroid gland is enlarged or has bumps (nodules). Depending on the results of the examination, other tests may also be needed. To determine how well the thyroid gland is functioning, doctors usually measure the levels of hormones in the blood. They measure levels of TSH T4 T3 Usually the level of thyroid-stimulating hormone in the blood is the best indicator of thyroid function. Because the role of this hormone is to stimulate the thyroid gland, blood levels of TSH are high when the thyroid gland is underactive (and thus needs more stimulation) and low when the thyroid gland is overactive (and thus needs less stimulation). However, in rare cases in which the pituitary gland is not functioning normally, the level of TSH does not accurately reflect thyroid gland function. and in people in the early stages of Overview of Acute Viral Hepatitis . If a doctor feels one or more growths (nodules) in the thyroid gland, an ultrasound procedure may be done. Ultrasonography uses sound waves to measure the size of the gland and to determine whether the growth is solid or filled with fluid (cystic), what the characteristics of the nodule are such as the presence or absence of calcium, as well as the vascularity of the thyroid. In another test (called a radioactive iodine uptake test—a type of Radionuclide Scanning ), a small amount of a radioactive substance (such as iodine or technetium) is injected into the bloodstream. The radioactive material concentrates in the thyroid gland, and a device (gamma camera) does another type of scan that detects the radiation and produces a picture of the thyroid gland that shows any physical abnormalities. Because the thyroid gland takes up radioactive iodine depending on how well it is working, a thyroid scan can also help determine whether the functioning of a specific area of the thyroid is normal, overactive, or underactive compared with the rest of the gland. If doctors suspect an Autoimmune Disorders , a blood test is done to look for antibodies that are attacking the thyroid gland. If Thyroid Cancer is suspected, doctors use a small needle to obtain a sample of thyroid tissue for study (a biopsy). Doctors usually use ultrasonography to identify the site to biopsy. When medullary thyroid cancer is suspected, blood levels ofcalcitoninare measured, because these cancers always secretecalcitonin. Some experts recommend screening for thyroid disease by measuring the level of thyroid stimulating hormone in the blood every year or every few years in people older than 70 years old; however, a number of medical bodies that have examined this question recommend against screening truly asymptomatic adults in order to avoid over-treating people with minor laboratory abnormalities. Screening is recommended for all newborns to detect congenital hypothyroidism, which can cause major defects in development of the brain and other organs if left untreated. 