How are patients screened for Graves disease?

Updated: Apr 17, 2020
  • Author: Sai-Ching Jim Yeung, MD, PhD, FACP; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Ultrasensitive (third-generation) thyrotropin assays remain the best screening test for thyroid disorders.

  • With the exception of thyrotropin-induced hyperthyroidism, subnormal or suppressed thyrotropin levels are seen in most patients with thyrotoxicosis.

  • Free T4 levels or the free T4 index is usually elevated, as is the free T3 level or free T3 index. Subclinical hyperthyroidism, defined as a free T4 or free T3 level within the reference range with suppressed thyrotropin, also can be seen.

  • On occasion, only the free T3 level is elevated, a syndrome known as T3 toxicosis. This may be associated with toxic nodular goiter or the ingestion of T3. Elevated T3 levels are often seen in early phase Graves disease as well.

  • Assays for thyrotropin-receptor antibodies (particularly TSIs) almost always are positive.

  • Detection of TSIs is diagnostic for Graves disease.

  • The presence of TSIs is particularly useful in reaching the diagnosis in pregnant women, in whom the use of radioisotopes is contraindicated.

  • Other markers of thyroid autoimmunity, such as antithyroglobulin antibodies or antithyroidal peroxidase antibodies, are usually present.

  • Other autoantibodies that may be present include thyrotropin receptor–blocking antibodies and anti–sodium-iodide symporter antibody.

  • The presence of these antibodies supports the diagnosis of an autoimmune thyroid disease.

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