Diagnosis

Measuring the level of thyroid-stimulating hormone (TSH), produced by the pituitary gland in the blood is typically the initial test for suspected hyperthyroidism. A low TSH level typically indicates that the pituitary gland is being inhibited or "instructed" by the brain to cut back on stimulating the thyroid gland having sensed increased levels of T4 and/or T3 in the blood.

Measuring specific antibodies, such as anti-TSH-receptor antibodies in Graves' disease, or anti-thyroid-peroxidase in Hashimoto's thyroiditis—a common cause of Hypothyroidism—may also contribute to the diagnosis.

The diagnosis of hyperthyroidism is confirmed by blood tests that show a decreased thyroid stimulating hormone (TSH) level and elevated T4 and T3 levels. TSH is a hormone made by the pituitary gland in the brain that tells the thyroid gland how much hormone to make. When there is too much thyroid hormone, the TSH will be low.

In addition to testing the TSH levels, many doctors test for T3, Free T3, T4 and/or Free T4 for more detailed results. Typical adult limits for these hormones are:

TSH: 0.45 - 4.50 uIU/mL

FT3 2.5 – 6.0 pmol/L

FT4: 9 – 19 pmol/L

TT3: 1.2 – 3.2 nmol/L

TT4: 65 – 155 nmol/L

T4 Free/Direct (nanograms): 0.82 - 1.77 ng/dl;

T3 (nanograms): 71 - 180 ng/dl.

So take a blood test is a direct method to check whether you get hyperthyroidism. Of course, you can check the symptoms you get and compare the symptoms of hyperthyroidism we listed at our FAQ Q56 You may get hyperthyroidism if you get more than 2 symptoms listed there.

* The result will be varied from lab to lab. So patients need to show the normal range of each figures.