Ft3 (Free T3)

You should get a Free T3 test if you have symptoms of hyperthyroidism, such as weight loss, palpitations, anxiety, sweating, or tremors, especially when TSH is low but FT4 is normal. It is also recommended for evaluating hypothyroidism, monitoring Graves' disease or anti-thyroid treatment, and assessing thyroid function during serious illness.

No special preparation or fasting is required for a Free T3 test. Give your sample in the morning, and take your thyroid medicine after the sample unless your doctor advises otherwise. Stop biotin supplements 48–72 hours before the test, as biotin can interfere with results. Inform your doctor about pregnancy or other medications.

No, fasting is not required for a Free T3 test. You can eat and drink normally before giving your sample. A morning sample is preferred, and you should take your thyroid medicine after the test unless your doctor advises otherwise. Stop biotin supplements 48–72 hours beforehand, as biotin can affect results.