Basics
Thyroid gland produces T4 and T3 hormones which regulate metabolism (sympathetic drive and thermo-regulation)
TSH secreted by pituitary gland stimulates thyroid hormone production
Iodine is needed to make thyroid hormones (iodine is found in seafood, cod liver oil, iodine-supplemented salt)

Presentation
Weight loss, hot and sweaty, tremor, anxiety, diarrhoea. Goitre. Eye disease – proptosis. Myxoedema. Thyroid ‘storm’

Complications
Atrial fibrillation, osteoporosis

Causes of hyperthyroidism
Grave’s disease (autoimmune) – normal size gland
Toxic multinodular goitre (?iodine excess) – goitre/nodules
Thyroiditis (due to IV iodine containing contrast, post-partum) – tender gland

Investigations
TSH, free T4 and T3, Thyroid receptor antibodies

• typically low TSH, raised T4/T3. Antibodies raised in Grave’s disease
  Thyroid uptake scan if no antibodies to identify toxic nodules
  CRP if suspect thyroiditis

Management of Grave’s disease
Symptomatic – beta blockers (non-selective eg. propranolol) – diltiazem can be used if asthmatic
Early anti-thyroid medication :
carbimazole/PTU – Patients with mild hyperthyroidism, a minimally enlarged thyroid and/or only modestly elevated TRAb levels are particularly good candidates for a trial of thionamide therapy as they have the best chance of achieving a durable remission.
carbimazole shouldn’t be used in 1st trimester of pregnancy
carbimazole/PTU can cause agranulocytosis and hepatitis (check FBC, LFT prior to initiation and warn re fever/sore throat to recheck FBC as risk of sepsis).
Radioactive iodine – benefit of long term cure rate of 75% (but usually end up hypothyroid)
Thyroidectomy – permanent resolution, can improve Grave’s orbitopathy, useful if compressive symptoms of large goitre, but end up hypothyroid, risk of hypoparathyroidism and recurrent laryngeal nerve injury

Weight gain can be an issue after treating hyperthyroidism as can increase more rapidly than prior weight loss