Blood Test for Thyroid Diagnostics A blood test is usually the
first test conducted to monitor thyroid function and the
production of thyroid hormones. TSH is the most sensitive index
of thyroid function and stimulated the thyroid gland to produce
thyroid hormone. Low TSH indicates that the thyroid is producing
too much hormone while an elevated TSH means too little thyroid
hormone is being produced. Therefore, high levels of thyroid
hormones and a low TSH indicate hyperthyroidism while low levels
of thyroid hormones and a high TSH are indicative of
hypothyroidism. If an autoimmune thyroid condition is suspected
(Hashimoto's thyroiditis), then anti-thyroid peroxidase and
antithyroglobulin antibody measurements in the blood may be made
to confirm the diagnosis. Other thyroid hormones that can be
measured in the blood include: T3, T4, thyroid peroxidase (TPO),
thyroid antibody (Tgab), TSH receptor antibody, and thyroid
binding immunoglobulin. In addition, measurements of
thyroglobulin may be performed. Such a m