Hypothyroidism is a condition in which the thyroid gland does not produce enough hormones, specifically thyroxine (T4) and triiodothyronine (T3). These hormones are essential for regulating metabolism, growth, and development. When there is a deficiency of these hormones, it can lead to various symptoms such as fatigue, weight gain, sensitivity to cold, constipation, dry skin, hair loss, depression, and slow heart rate. Hypothyroidism can be caused by factors such as autoimmune disease, iodine deficiency, radiation therapy, or removal of the thyroid gland. Treatment typically involves hormone replacement therapy with synthetic T4 (levothyroxine) to restore normal hormone levels and alleviate symptoms.