L-thyroxine (levothyroxine)

L-thyroxine, commonly known as levothyroxine, is a manufactured form of the hormone thyroxine (T4) that the thyroid gland naturally produces. It's used to treat hypothyroidism, a condition where the thyroid doesn't produce enough hormones, leading to symptoms like fatigue, weight gain, and depression. By providing synthetic thyroid hormone, levothyroxine helps restore normal metabolic function, energy levels, and overall balance. It's typically taken daily in pill form and requires monitoring to ensure the correct dose, as both too little and too much can cause health issues.