FT3 IS USED TO EVALUATE THYROID FUNCTIONS, WHICH T3 IS THYROID HORMONES IN WHICH IT OCCURS IN TWO DIFFERENT STATES IN THE BODY BOUND TO A PROTEIN AND FREE "NOT BOUND TO PROTEIN". T3 IS USED TO DIAGNOSE HYPERTHYROIDISM AND TO CLARIFY THYROID STATUS IN THE PRESENCE OF A POSSIBLE PROTEIN BINDING ABNORMALITY. SYMPTOMS OF A LOW THYROID MAY RESULT IN FATIGUE, DRY SKIN, AND EXCESSIVE WEIGHT GAIN.