Hello, Hypothyroidism may classically cause menorrhagia, probably as a consequence of anovulatory dysfunctional uterine bleeding, but it is a rare cause of this symptom. Most women with untreated hypothyroidism will develop amenorrhoea. The connection between thyroid hormone levels and the menstrual cycle is mainly mediated by thyrotropin-releasing hormone (TRH), which has a direct effect on the ovary. Additionally, abnormal thyroid function can alter levels of sex hormone-binding globulin, prolactin, and gonadotropin-releasing hormone, contributing to menstrual dysfunction. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Elona Xhardo, Endocrinologist