Thyroid Diseases

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:

• Thyroid antibodies - to help differentiate different types of thyroiditis and identify autoimmune thyroid conditions
• Calcitonin - to help detect the presence of excessive calcitonin production

Screening

Screening for thyroid disease is controversial, and there is no consensus in the medical community as to who would benefit from scrrening 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 adults. However, the American Thyroid Association currently recommends that everyone over 35 years of age be screened with a TSH test every 5 years, and the American Association of Clinical Endocrinologists recommends that all women be tested for hypothyroidism by 50 years of age (sooner if they have a family history of thyroid disease) as well as those who are or planning to become pregnant in order to detect thyroid problems.

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