The DRG:HYBRiD-XL T3 is an enzyme immunoassay for the quantitative in vitro diagnostic measurement of total Triiodothyronine (T3) in serum and plasma.Only for use with the DRG:HYBRiD-XL Analyzer.Triiodothyronine, also known as T3, is produced in the thyroid gland, the liver, the kidney and peripheral organs from its precursor thyroxine (T4). T3 affects almost every physiological process in the body, including growth and development, metabolism, body temperature, and heart rate. Production of T3 and T4 is induced by thyroid-stimulating hormone (TSH), which is released from the pituitary gland. This pathway is regulated via loop feedback process. More than 99.6% of T3 is bound to serum proteins, especially to Thyroxin binding globulin, but also to Transthyretin and Albumin. T3 is a useful marker of thyroid function. Levels of T3 and T4 are decreased in hypothyroidism andincreased in hyperthyroidism. The DRG:HYBRiD-XL T3 Kit is a solid phase enzyme-linked immunosorbent assay (ELISA) based on the principle of competitive binding. The antibody coated wells (ACW) of the reagent cartridges are coated with a polyclonal antibody directed towards a unique antigenic site of the T3 molecule. Endogenous T3 of a patient sample competes with a T3-horseradish peroxidase conjugate for binding to the coated antibody. After incubation the unbound conjugate is washed off. The amount of bound peroxidase conjugate is inversely proportional to the concentration of T3 in the sample. Having added the substrate solution, the intensity of colour developed is inversely proportional to the concentration ofT3 in the patient sample.