STANDARD F T3 is a fluorescent immunoassay for the quantitative measurement of Thyroid Stimulating Hormone level in human serum. This test is to help diagnose thyroid disorder; to monitor the treatment of hypothyroidism and hyperthyroidism. STANDARD F T3 is a fluorescent immunoassay for the quantitative measurement of Thyroid Stimulating Hormone level in human serum. This test is to help diagnose thyroid disorder; to monitor the treatment of hypothyroidism and hyperthyroidism.