Hello there,Welcome to HCM. Yeah,its a scenario which we sometimes see and in such cases there are few conditions which a doctor thinks of. 1)You are getting Thyroxine(drug for thyroid hormone replacement) more than requirement and it could be simply because after child birth your body requirement of thyroid has decreased because pregnancy is a condition where your body requires more thyroid hormone 2)Immediately after delivery the thyroid function fluctuates because of the changes in the body and this could be causing your thyroid to release more thyroid hormone. 3)The iron and calcium supplementation which are prescribed during pregnancy interfere with the absorption of thyroxine and there stopping after delivery could be a cause of increase absorption of thyroxine leading to hyperthyroidism 4)Thyroid hormone replacement is a trial and error method and there may be over estimation of your dose requirement and your doctor may eventually set the right dose based on subsequent thyroid levels. 4)Post partum thyroiditis:-Its a condition where due to some unknown cause there is inflammation of thyroid gland leading to secretion of more throid hormone than usual and this may cause mild hypothyroid state change into a hyperthyroid state. 5)In patient with hypothyroidism due to autoimmune cause(where body s own immune system destroys the throid gland) ,during natural course of the disease,the destroying thyroid gland tries to fight the situation and secretes more thyroid hormone in between before eventually getting totally destroyed and could be causing hyperthyroidism. 6)In a rare condition it could be coexistance of both Hyper thyroid disease(Grave s disease) and Hypothyroid (Hashimoto s disease).Here antibodies(immune particles of the body which are abnormally present in auto immune diseases) which are seen in both diseases are present. The treatment depends on the underlying cause and if there is more than required supplementation then the dose of thyroxine is to be cut down.If its a Thytoiditis it will usually resolve by itself and if you are symptomatic then your doctor may prescribe you beta blocker which relieves palpitations ,anxiety associated with hyperthyroidism.If you are having both Grave s and Hashimoto s (which is a rare condition) your thyroid levels will frequently be monitored and treated accordingly. To summarise this Hyperthyroid state is usually transient and if you are not a known hypothyroid then your thyroid levels may become normal but the chances of getting hypothyroidism in future will be more.If you are a known hypothyroid the likely course is you will again go back to hypothyroidism. Hope this will help you.Thank You.