Glossary On Diagnosis of Hyperthyroidism

The features of hyperthyroidism are characteristic of the condition; however, certain laboratory tests help to firmly establish the diagnosis and also to determine the cause hyperthyroidism.

Some of the tests required for diagnosis are:

• Thyroid hormone T3 and T4 levels: These will be higher than normal in cases of hyperthyroidism. T4 levels are high in the early stages whereas T3 levels rise in the later stages of the disease.
• Thyroid Stimulating Hormone (TSH) level: This will be lower than normal in case of Hyperthyroidism since high levels of T3 and T4 in the blood provide a negative feedback to the pituitary thereby reducing the release of TSH.
• Thyroid Scan with radioactive iodine: This shows whether the excess thyroid hormones are being secreted by the entire gland or one or more nodules (Hot Nodules) in the gland.
• Iodine Uptake Scan: This test measures the amount of iodine that is taken up by the Thyroid gland. Patients with hyperthyroidism take up too much of iodine.
• Thyroid Ultrasound: An ultrasound of the thyroid gland determines the presence of thyroid nodules and also whether they are solid or cystic (fluid-filled) in nature.
• Thyroid stimulating immunoglobulin or TSI – the presence of thyroid stimulating antibodies indicates Graves’ disease. In such cases, these immunoglobulins stimulate the thyroid to produce excess amounts of hormones resulting in a hyperthyroid state.