A thyroxine test helps diagnose disorders of the thyroid. The thyroid is a small, butterfly-

shaped gland located near the throat. Your thyroid makes hormones that regulate the way your

body uses energy. It also plays an important role in regulating your weight, body temperature,

muscle strength, and even your mood. Thyroxine, also known as T4, is a type of thyroid

hormone. This test measures the level of T4 in your blood. Too much or too little T4 can

indicate thyroid disease.