How is thyroid function measured?
A series of blood tests (thyroid function tests) can be used to establish whether the level of circulating thyroid hormone is normal, raised or lowered. Diagnosis of the precise cause of abnormal thyroid function is complex and may involve measurement of pituitary hormone output (TSH), uptake of radioactive isotopes of iodine, ultrasound scanning or computerised axial tomography (CAT) of the thyroid gland. Additional tests to identify or exclude other systemic disease that may affect thyroid function may also be needed.
