Your doctor will examine your medical history and analyse your blood test report to diagnose the prevalence of hyperthyroidism. If your blood test indicates hyperthyroidism, the doctor will further conduct TSH, T4 (or Free T4), T3 (or Free T3) and Radioactive Iodine Update (RAI-U) tests to confirm it. TSH, T4 (or Free T4), T3 (or Free T3) tests measure the level of different hormones that affect thyroid production. Radioactive Iodine Update (RAI-U) test determines if hyperthyroidism is caused by Grave’s disease or something else.[Read: Diagnosis of Hyperthyroidism]
Hyperthyroidism is diagnosed using:
- Thyroid-Stimulating Hormone (TSH) Test— It is the primary test, which your doctor will perform to diagnose hyperthyroidism. The suppressed level of thyroid-stimulating hormone (which is produced by the pituitary gland) is characteristic of hyperthyroidism. TSH test gives the accurate measure of this hormone present in your blood and it is significantly useful in diagnosing the presence of mild hyperthyroidism. When the thyroid gland starts producing excessive amount of thyroid hormone, the pituitary glands stop TSH production leading to considerably low TSH levels in the blood. If the findings of the TSH test are below the normal TSH range, you are hyperthyroid and if it exceeds the normal range, you have hypothyroidism.
- Triiodothyronine (T3) Test— There are two types of T3 tests, namely total triiodothyronine test and free triiodothyronine test. Total Triiodothyronine Test— People with hyperthyroidism have increased levels of total triiodothyronine (T3) whereas in hypothyroid patients, T3s levels are low.
- Free Triiodothyronine Test —This hyperthyroidism test is known to present more accurate results than total triiodothyronine (T3) test. It determines the unbound levels of triiodothyronine in your blood. Free T3 levels are elevated in hyperthyroidism.
- Thyroxine (T4) Test— The two types of T4 tests are free thyroxine (T4) test and total thyroxine test. Free T4 measures the free thyroxine levels in your blood. Like T3, the level of T4 increases in hyperthyroidism and decreases in hypothyroidism. It is considered a better thyroid indicator than total T4, which determines the total amount of thyroxine in your blood circulation.
- Radioactive Iodine Update (RAI-U) Test— This test determines the thyroid gland’s ability to absorb iodine. This helps the doctor to know whether the thyroid gland is functioning properly or not. Radioactive Iodine Update (RAI-U) test finds the cause of the onset of hyperthyroidism and its appropriate treatment plan. This hyperthyroidism test detects the prevalence of Grave’s disease, which is a risk factor for hyperthyroidism. [Read: Treatment of Hyperthyroidism]
Your doctor may conduct a single test or a combination of tests. '
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