A 45-year-old woman presents with lethargy, weight gain and cold intolerance. TSH is 18 mIU/L and free T4 is low. She is not pregnant and has no cardiac disease. What is the most appropriate initial management?AStart carbimazoleBStart levothyroxine 50 micrograms orally once daily and review thyroid function in 6-8 weeksCStart liothyronine 20 micrograms three times dailyDReassure; no treatment is needed as TSH is below 20 mIU/LEStart high-dose glucocorticoidsCheck my answer