Blood Test Includes:
Free thyroxine index (FTI)
T3 uptake (THBR)
Thyroid-stimulating hormone (TSH)
The Thyroid antibody blood testing is primarily ordered to help diagnose an autoimmune thyroid disease and to separate it from other forms of . It may be ordered to help investigate the cause of a goiter and/or performed as a follow-up when other thyroid test results (such as T3, T4, and/or TSH) show signs of thyroid dysfunction.
One or more thyroid antibody blood tests may also be ordered if a person with a known non-thyroid-related autoimmune condition, such as systemic lupus erythematosus, rheumatoid arthritis, or pernicious anemia, develops symptoms that suggest thyroid involvement. This involvement may occur at any time during the course of the other condition(s).
If a pregnant woman has a known autoimmune thyroid disease (such as Hashimoto’s thyroiditis or Graves’ disease) or has another autoimmune disorder and thyroid involvement is suspected, then one or more of the thyroid antibodies may be ordered early in the pregnancy and then again near the end. These blood tests are used to help the doctor determine whether the baby may be at risk of thyroid dysfunction since thyroid antibodies can cross the placenta and cause hypothyroidism or hyperthyroidism in the fetus or newborn.
Thyroid antibody blood testing may also be ordered when a patient with another autoimmune disorder has symptoms of thyroid dysfunction and/or when she has reproductive difficulties that the doctor suspects may be associated with autoantibodies.