Final answer:
Myxedema coma occurs when there is a severe deficiency of thyroid hormone, resulting in hypothyroidism.
Step-by-step explanation:
Myxedema coma occurs when there is a severe deficiency of thyroid hormone. This condition, known as hypothyroidism, is characterized by a low metabolic rate, weight gain, sensitivity to cold, and reduced mental activity. It can be caused by a disease of the thyroid gland, a disease of the pituitary or hypothalamus, or a deficiency of iodine.