What should you know about secondary hyperthyroidism symptoms?

Hyperthyroidism means thyroid hormone activity is higher than the body needs. In secondary hyperthyroidism, the thyroid is being driven by a problem outside the thyroid itself, so the underlying cause matters. People may notice a fast or forceful heartbeat, feeling unusually warm, excessive sweating, night sweats, loose stools, restlessness or trouble sleeping. Feeling anxious can occur because excess thyroid hormone stimulates body systems involved in alertness. Symptoms may appear together or develop gradually, and their intensity does not by itself identify the cause.

Arrange a clinical review if these symptoms are persistent, new, or occurring in combination. Keep a brief record of when palpitations, sweating, bowel changes or sleep disruption occur, and list medicines, supplements and recent illnesses. A clinician may examine your pulse and neck and request blood tests that assess thyroid activity and its control signals. Do not change prescribed treatment or start thyroid products without advice. For background, see Hyperthyroidism and the symptom pages for Palpitations, Heat Intolerance, Excessive Sweating, Night Sweats, Diarrhoea, Feeling Anxious and Difficulty Sleeping.

Seek urgent medical help for chest pain, fainting, severe breathlessness, confusion, or a very rapid or irregular heartbeat with marked weakness. Contact a clinician promptly if vomiting, diarrhoea, sweating or heat intolerance is causing difficulty keeping fluids down, or if symptoms are worsening quickly. Urgency is based on the symptom and how unwell you feel, not on assuming that a symptom proves a thyroid disorder.

Could another condition, medicine or supplement be driving these thyroid symptoms? Which blood tests are needed, and when should they be repeated? What symptoms should prompt urgent help?