How concerned should i be of myxedema coma?

Very concerned: With modern screening for hypothyroidism this isn't seen as commonly, but it is a life threatening condition that needs to be treated in a hospital. Frequently patients require intensive care and there can be deaths even when it is treated appropriately. It usually takes a long time to develop and regular health screenings should prevent it from ever getting to this stage.

Myxedema coma: Myxedema coma typically occurs as a result of long-standing hypothyroidism, and follows a period of progressive symptoms. These symptoms may include weight gain, somnolence, and weakness amongst others. Abrupt discontinuation of thyroid hormone could also precipitate a myxedema coma.