How is an overactive thyroid diagnosed?
Palpitations, tremor, weight loss and heat intolerance can suggest hyperthyroidism. Assessment uses TSH and thyroid hormone tests. Symptoms or a low TSH alone do not establish the cause or the correct treatment.
Details
Symptoms overlap with other conditions
Sweating, anxiety, disturbed sleep and frequent bowel movements may occur, but not everyone has the same pattern. Older adults can present differently. Unexplained weight change or palpitations should not automatically be attributed to anxiety without assessment.
From a result to the cause
Low TSH with raised free thyroxine or triiodothyronine supports the usual diagnosis. Antibody tests or imaging may distinguish Graves’ disease, active nodules and thyroiditis. Report thyroid medicines, supplements and pregnancy before investigations are chosen.
When is assessment urgent?
Palpitations with chest pain, fainting or breathlessness need urgent assessment. High fever with a racing heart and altered awareness can signal an emergency. Do not start antithyroid medicine because your symptoms resemble someone else’s.
Related reading: What are hypothyroidism symptoms, and how is it diagnosed?.