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Thyroid Diseases

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Laboratory Tests

The first test your doctor will usually order to detect thyroid dysfunction is a TSH test. If your TSH level is abnormal, the doctor will usually order a total T4 or free T4 test to confirm the diagnosis. A total T3 or free T3 test may be ordered as well.

  • TSH – to test for hypothyroidism, hyperthyroidism, screen newborns for hypothyroidism, and monitor thyroid replacement therapy
  • T4 or free T4 – to test for hypothyroidism and hyperthyroidism and to screen newborns for hypothyroidism
  • T3 or free T3 – to test for hyperthyroidism

Additional tests that may be performed include:


Screening for thyroid disease is controversial, and there is no consensus in the medical community as to who would benefit from screening and at what age to begin. In 2004, the U.S. Preventive Services Task Force found insufficient evidence to recommend for or against routine screening for thyroid disease in asymptomatic adults. The American Thyroid Association and the American Association of Clinical Endocrinologists released clinical practice guidelines in 2012 that recommend that screening for hypothyroidism should be considered in patients over the age of 60.

Non-Laboratory Tests

  • Thyroid Scans – a test that uses radioactive iodine or technetium to look for thyroid gland abnormalities and to evaluate thyroid function in different areas of the thyroid
  • Ultrasound – an imaging scan that allows doctors to determine whether a nodule is solid or fluid-filled and can help measure the size of the thyroid gland
  • Biopsies – often a fine-needle biopsy, a procedure that involves inserting a needle into the thyroid and removing a small amount of tissue and/or fluid from a nodule or other area that the doctor wants to examine; an ultrasound is used to guide the needle into the correct position.

For more on imaging studies, see the web site

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