A Thyroid Function Panel Test measures the levels of hormones produced by the thyroid gland to assess its function. The test typically includes checking Thyroid Stimulating Hormone (TSH), Free T4 (Thyroxine), and Free T3 (Triiodothyronine). These hormones regulate metabolism, energy levels, and other important body functions. Abnormal results can indicate hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid), leading to conditions such as weight gain, fatigue, or rapid heart rate.