FT4 and hyperthyroidism

FT4 is the free form of thyroxine, a thyroid hormone that influences how quickly the body uses energy. In hyperthyroidism, the thyroid may release too much hormone. People with hyperthyroidism often notice palpitations, heat intolerance, excessive sweating, feeling anxious, difficulty sleeping, weight change or diarrhoea. These symptoms can have other causes, so a blood result needs context. Medicines, supplements, pregnancy and acute illness can affect interpretation.

Review the FT4 and TSH together with your clinician, and provide a list of medicines and supplements. Do not alter thyroid treatment without instructions. Further assessment may include another thyroid marker, an examination of the neck, or a discussion of medicines and symptoms. Keep a note of new palpitations, tremor, bowel changes and sleep problems so the pattern is clear.

Seek emergency care for chest pain, severe breathlessness, fainting, confusion, collapse or a very fast heartbeat that does not settle. Contact your clinician promptly if sweating, diarrhoea, anxiety or palpitations are worsening, particularly after a thyroid medicine change. Do not wait for routine testing when symptoms are severe.

Ask whether your FT4 and TSH pattern indicates hyperthyroidism, what may be causing it, whether treatment is needed now, and which symptoms require urgent review.