What is the main cause of hyperthyroidism?

The most common cause is Graves’ disease, in which antibodies signal the thyroid to keep producing hormone. Other causes include a thyroid nodule that works independently, inflammation that releases stored hormone, or taking more thyroid hormone medicine than prescribed. Excess hormone speeds up several body systems. Possible presentations include palpitations, excessive sweating, heat intolerance, diarrhoea, difficulty sleeping, feeling anxious, or night sweats. These symptoms can also occur for other reasons.

Book a clinical assessment if symptoms persist, recur, or interfere with daily life. Blood tests usually measure thyroid-stimulating hormone and thyroid hormones; further testing may look for thyroid antibodies or examine the gland. Bring a list of medicines and supplements, including products containing iodine or thyroid hormone. Treatment depends on the cause and may include medicine, radioiodine, or surgery, so it should be selected with a clinician.

Seek urgent help for a very fast or irregular heartbeat with chest pain, fainting, severe breathlessness, marked agitation, confusion, or a high fever. Arrange prompt review if palpitations are new, you are losing weight without intending to, or you are pregnant. Untreated excess thyroid hormone can place strain on the heart and bones.

Ask which thyroid tests are needed, whether Graves’ disease or a nodule is suspected, how treatment affects other medicines, and which symptoms should trigger urgent help.