Thyroid hormones, particularly triiodothyronine (T3) and thyroxine (T4), are essential for regulating growth, metabolism, and energy usage in the body. Hyperthyroidism, marked by excess thyroid hormones, accelerates these processes, causing symptoms like weight loss, increased heart rate, and heightened energy metabolism.

Hyperthyroidism stems from several causes, including autoimmune Graves' disease, thyroid nodules, and excessive iodine intake. Symptoms range from weight loss to heart issues and bone problems like osteoporosis. Diagnosis relies on lab tests for TSH, T4, and T3 levels, alongside imaging to determine the cause. Treatment varies from antithyroid medications to radioactive iodine or surgery, depending on the condition's severity and underlying cause.