What Causes Hyperthyroidism?

The cause matters because the thyroid may be producing new hormone, or hormone already stored in the gland may be leaking into the bloodstream. These situations can look similar at first but may need different treatment.

Graves’ disease is an immune-system condition in which antibodies stimulate the thyroid to make too much hormone. Other causes include one or more thyroid nodules that produce hormone independently of the body’s usual controls. Thyroiditis, or inflammation of the thyroid, can release stored hormone for a period before the gland settles or becomes underactive.

Taking more thyroid hormone than prescribed can also raise hormone levels. Some supplements and medicines may contain thyroid hormone or affect thyroid testing. Pregnancy-related changes and problems affecting the pituitary gland are less common contributors and need clinical assessment.

Possible effects include a fast or irregular heartbeat, feeling anxious, trouble sleeping, heat intolerance, excessive sweating, diarrhoea, shakiness, and unintended weight loss. A symptom such as palpitations can occur with hyperthyroidism, but it does not by itself establish the cause.

Arrange a medical review if symptoms suggest excess thyroid hormone or if a blood test has shown an abnormal thyroid result. A clinician will ask about symptoms, medicines, supplements, recent illness, pregnancy or postpartum changes, and any history of thyroid disease.

Testing commonly starts with thyroid-stimulating hormone and thyroid hormone measurements. Depending on the results, examination and medical history, further blood tests or thyroid imaging may help distinguish immune stimulation, nodules, inflammation, or an external source of hormone. Do not stop prescribed thyroid medicine without advice; bring the product name and dose to the appointment.

Seek urgent medical help for chest pain, fainting, severe breathlessness, confusion, or a very fast or irregular heartbeat, especially with fever, vomiting, or marked agitation. These symptoms can signal a serious complication requiring prompt treatment.

Contact a clinician soon if symptoms are persistent, worsening, or interfering with sleep and daily activities. Mention new supplements, a recent infection, pregnancy or recent delivery, and any change in thyroid medicine because each can alter the likely explanation.

You could ask: Which cause best fits my symptoms and test results? Should I have antibody testing or a scan? Could any medicine, vitamin, or supplement be affecting my thyroid? What symptoms should prompt urgent help while I am being assessed?