Thyroxine, also known as T4, is a hormone produced by the thyroid gland in the neck. It is essential for regulating the body’s metabolism and controlling many life activities, such as growth and development, body temperature, and heart rate. It is also important in maintaining energy balance and in the synthesis of proteins and other molecules, such as neurotransmitters. Without adequate levels of thyroxine, the body can become sluggish, resulting in fatigue, weight gain, muscle and joint pain, depression, and other health issues. Low thyroxine levels can also lead to an underactive thyroid, which can cause a host of other complications. Therefore, maintaining healthy levels of thyroxine is essential for maintaining overall health and well-being.