Section 862.1710 - Total triiodothyronine test system(a)Identification. A total triiodothyronine test system is a device intended to measure the hormone triiodothyronine in serum and plasma. Measurements obtained by this device are used in the diagnosis and treatment of thyroid diseases such as hyperthyroidism.(b)Classification. Class II. This device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 862.9 .52 FR 16122, May 1, 1987, as amended at 65 FR 62286 , Oct. 18, 2000