本试剂盒应用竞争抑制酶标免疫分析法测定标本中T3水平。用纯化的抗体包被微孔板，制成固相抗体，固相抗体与一定量的生物素标记的T3和非标记抗原(标本或标准品)进行竞争抑制反应，待测定的标本量越多，抗体与生物素标记的T3结合就越少，反之结合就多。最后再加入HRP标记的亲和素，经过彻底洗涤后用底物TMB显色。TMB在过氧化物酶的催化下转化成蓝色，并在酸的作用下转化成最终的黄色。颜色的深浅和样品中的T3呈负相关。用酶标仪在450nm波长下测定吸光度（OD值），计算样品浓度。
Intended use
This immunoassay kit allows for the specific measurement of total T3 concentrations of natural and recombinant human T3 in plasma and serum.
Introduction
Under normal physiological conditions, T3 represents approximately 5 percent of the thyroid hormones in serum. Although present in lower concentration, T3 has a greater intrinsic metabolic activity, faster turnover and larger volume of distribution than circulating T4.1 Reports that thyrotoxicosis may be caused by abnormally high concentrations of T3 —rather than T4 — have reinforced the importance of T3 measurements. In addition, T3 determination is an important tool for monitoring hypothyroid patients receiving sodium liothyronine therapy. Unlike "T3 Uptake" tests, which estimate the saturation of thyroid hormone binding proteins, total T3 analysis measures circulating levels of triiodothyronine. Most reports indicate that T3 levels distinguish clearly between euthyroid and hyperthyroid subjects, but provide a less clear-cut separation between hypothyroid and euthyroid subjects. Numerous conditions unrelated to thyroid disease may cause abnormal T3 values. Consequently, total T3 values should not be used on their own in
establishing the thyroid status of an individual. The levels of serum T4, TBG (thyroid binding globulin), TSH (thyroid stimulating hormone) and other clinical findings must be considered as well.
Test principle
This assay employs the competitive inhibition enzyme immunoassay technique. A monoclonal
antibody specific for T3 has been pre-coated onto a microplate. A competitive inhibition reaction is launched between biotin labeled T3 and biotin unlabeled antigens (Standards or samples) with the pre-coated antibody specific for T3. The more the amount of T3 in samples, the less the biotin labeled T3 bound by pre-coated antibody. Vice versa. Then HRP labeld avidin and substrate solution are added to the wells, respectively. And the color develops in opposite to the amount of T3 bound in the initial step. The color development is stopped and the intensity of the color is measured.
