A thyroid profile test is a blood test that helps evaluate how well your thyroid gland is functioning. It commonly measures TSH, T3 and T4 hormone levels to identify thyroid-related conditions such as hypothyroidism and hyperthyroidism. Doctors may recommend this test if you experience unexplained weight changes, persistent fatigue, hair loss, irregular periods, mood changes or difficulty tolerating heat or cold. Thyroid testing may also be recommended during pregnancy or to monitor existing thy