Follicular cells (also called thyroid epithelial cells or thyrocytes) are present in the thyroid gland which is responsible for the production of hormones thyroxine (T4), triiodothyronine (T3) and calcitonin. Hypothyroidism is a condition in which body has low thyroid hormone. The main purpose of thyroid hormone is to "run the body's metabolism," it is understandable that people with this condition will have slow metabolism. Hypothyroidism signs and symptom may include: fatigue, increased sensitivity to cold, constipation, dry skin, weight gain, puffy face etc... Myxedema coma is a loss of brain function as a result of severe, longstanding low level of thyroid hormone in the blood (hypothyroidism).