Tests for diagnosing Hyperthyroidism

Analytical tests. A diagnosis of hyperthyroidism is confirmed by tests that measure the level of active (free, not protein-bound) thyroid hormones –free thyroxine (T4L) and free triiodothyronine (T3L), and thyroid-stimulating hormone, thyrotropin (TSH) in the blood.  

A high level of thyroid hormones (T4L and T3L) with low levels of TSH indicates hyperthyroidism or thyrotoxicosis.  

In pituitary forms, high levels of T4L and T3L with high TSH are found.  

General biochemical parameters such as cholesterol, liver transaminases or blood glucose may show transient variations in the course of the disease due to the fact that the thyroid is the main controller of metabolism. In cases of hyperthyroidism, thyroid-associated antibodies are studied to determine the cause. 

Imaging tests. Thyroid ultrasound is often used to study the cause of hyperthyroidism, to see whether there are any nodules (nodular or multinodular goitre) or not (Graves' disease or thyroiditis). Thyroid scintigraphy may also be used to study the cause of thyrotoxicosis to see if the thyroid is overactive in general, if there are overactive (toxic) nodules, or if the thyroid is blocked or inflamed (thyroiditis).