Synopsis
Choose safely between medical control, radioiodine and thyroidectomy for hyperthyroidism while anticipating toxicity, relapse, eye disease, fertility implications and peri-operative risk.
- First establish the cause of thyrotoxicosis. Graves' disease, toxic nodular disease and destructive thyroiditis do not share the same response to antithyroid medicines or radioiodine.
- Carbimazole is usual first-line antithyroid treatment for many non-pregnant adults; propylthiouracil is reserved for defined situations because serious hepatic injury is an important risk.
- Before starting an antithyroid medicine, obtain full blood count and liver tests. Routine serial counts do not replace urgent testing when fever, sore throat or mouth ulcers develop.
Key red flags
Fever, sore throat, oral ulceration, jaundice, dark urine, severe pruritus or abdominal pain during antithyroid therapy demands urgent assessment. Agranulocytosis and hepatic injury can progress despite an apparently modest dose.
Investigation priorities
Confirm biochemical severity and provide a baseline for response.
Management branches
Synthesis-driven Graves' disease or temporary control of nodular hyperthyroidism while definitive care is arranged.
- Confirm cause, obtain baseline blood count and liver tests, review pregnancy possibility and interactions, then select carbimazole or a defined propylthiouracil indication.
- Give written agranulocytosis and hepatic warning advice. Recheck free hormones at the local early interval and adjust by titration or a specialist-agreed block-and-replace plan.
Key medicines
CarbimazoleInitial and maintenance dose depend on biochemical severity and whether titration or block-and-replace is chosen; follow BNF and specialist review.
PropylthiouracilUse a specialist-selected divided regimen only for a defined indication, with dose reduction as free hormones improve.