The thyroid produces two major hormones: triiodothyronine (T3) and thyroxine (T4).If your thyroid gland doesn’t produce enough of these hormones, you may experience symptoms such as weight gain, lack of energy, and depression. If your thyroid gland produces too many hormones, you may experience weight loss, high levels of anxiety, tremors, and a sense of being on a high. Typically, a doctor who is concerned about your thyroid hormone levels will order broad screening tests, such as the T4 or the thyroid-stimulating hormone (TSH) test.If you experience a great deal of pain, or if the area around the puncture becomes red and swollen, follow up with your doctor immediately. The T4 test and the TSH test are the two most common thyroid function tests. Symptoms include anxiety, unplanned weight loss, tremors, and diarrhea. A small portion of T4 is not and this is called free T4.Free T4 is the form that is readily available for your body to use.
Talk to your doctor about any medications you’re taking, and tell your doctor if you’re pregnant.During the days immediately after the blood draw, you may notice slight bruising or soreness at the area where the needle was inserted.