- Home Page
- Sales & Partners
- News & Events
- Site Map
|Method & Line||Sample & Target||Product||Package Info|
|IMMUNOgen - Immunoassays||Plasma,Serum||Free T3||Tests per Package: 100|
|IMMUNOgen||The Eclectica Free T3 assay for the Eclectica and Eclectica TiCA analysers has been designed for the quantitative determination of free Triiodothyronine (Free T3) in human serum and heparinized plasma. The method can be used to measure free thyroxine concentrations over the range of 0.26 to 31.30 pg/ml ( 0.4 to 48.2 pmol/l).||Code: 1708600||Package: 2 x 50|
Please pay attention to the revision of the document that must be the same as the revision reported in the box label.
In case of discrepancy please contact our Customer Care e-mail: firstname.lastname@example.org.
* Other document related to the product available at Documentation Centre and it is accessible for Adaltis distributors/partners after registration only.
The Eclectica Free T3 assay for the Eclectica analyzers has been designed for the quantitative determination of free Triiodothyronine (Free T3) in human serum and heparinized plasma. The method can be used to measure free thyroxine concentrations over the range of 0.26 to 31.30 pg/ml (0.4 to 48.2 pmol/l).
Triiodothyronine (3, 5, 3' triiodothyronine) or T3 is a thyroid hormone with a molecular weight of 651. In contrast to T4, which is exclusively a product of the thyroid gland, T3 is mainly produced in peripheral tissues by the 5-mono-deiodination of T4. In normal subjects about 80% of T3 produced by peripheral conversion, and about 20% is secreted by the thyroid (1). Evidence suggests that T3 is the most important thyroid hormone, and some authors contend that T4 may have no intrinsic activity and serves merely as a prohormone for T3 (2, 3).
Circulating levels of T3 can be influenced by changes in thyroid gland function or by alteration in the peripheral metabolism of T4.
In serum, T3 exists in a reversible equilibrium between two states, bound and free. T3 bound to serum binding proteins, primarily thyroxine binding globulin (TBG) and to a lesser degree albumin and prealbumin, represents greater than 99 % of the total T3 (3). However, it is the relatively small free fraction (approximately 0.3 % of total T3) that is generally recognized as the physiologically active fraction due to its ability to enter target cells (3, 4).
Total T3 levels may be altered by changes in the concentration of TBG, which is dependant on several non-thyroidal factors. Levels may be elevated when TBG concentration is increased as in pregnancy, hepatitis, congenital TBG elevation, and administration of estrogens (oral contraceptives) (5). Conversely, levels may be reduced when TBG concentration is decreased by such conditions as nephrosis, hepatic failure, congenital TBG deficiency, administration of androgens or large amounts of glucocorticoids (6). Despite the alterations in total T3 levels from the physiological states described above, thyroid function is not affected because the body acts to maintain constant levels of free T3 (3, 4). Thus clinically euthyroid patients remain euthyroid regardless of TBG fluctuations.
Measurement of Free T3 is most useful in the diagnosis of hyperthyroidism. In the majority of patients with this condition, both free T3 and free T4 levels are elevated. In some cases, however, the hyperthyroidism results solely from an increased production of T3 (T3 thyrotoxicosis) (7). In severe hypothyroidism, free T3 levels are usually low, but in moderate hypothyroidism they may be normal (7).
The first laboratory techniques for measuring free T3 consisted of indirect methods such as the free T3 index and the T3/TBG ratio. These tests involve the use of a total T3 determination in conjunction with a test which measures available TBG binding sites (T3 uptake test)in case of the free T3 index, and TBG concentration in the T3/TBG ratio. However, these indirect tests have limited diagnostic value in cases of abnormally high or low TBG levels, and also involve the performance of two assay procedures (4, 7). A variety of methods have been developed to allow a direct measurement of free T3 which employ techniques such as equilibrium dialysis, ultrafiltration, and column chromatography, but these methods are generally too laborious and time-consuming for routine use in the clinical laboratory (7). Immunoassay methods have gained wide acceptance as specific, sensitive and convenient alternatives to many traditional clinical chemistry methods. Yet difficulties have arisen in applying immunoassay methods to the measurement of free T3 due primarily to the requirement that the original equilibrium between free and bound T3 must not be significantly disturbed by the assay reagents (4, 7).
The Eclectica Free T3 assay employs technology that allows the use of a conventional EIA methodology, whilst minimising the disturbance to the free and bound T3 equilibrium. Two key factors allow a direct measurement of Free T3. They are : (1) a T3 - Alkaline Phosphatase conjugate which binds to anti-T3 antibody but not significantly to TBG and other serum binding proteins; and (2) a monoclonal antibody with high affinity for T3.
The Eclectica assays for the Eclectica analyzers consists of:
In the Eclectica Free T3 assay, a mouse monoclonal anti-T3 antibody is used in an enzyme immunoassay system which incorporates magnetic solid phase separation. All incubation times and reagent volumes are determined by an assay specific software protocol.
Fixed amounts of fluorescein-labelled anti-T3 antibody and T3 conjugated to alkaline phosphatase are added to the sample, control or calibrators.
The reactants are incubated at 37°C. During the incubation free T3 in the sample, control or calibrators competes with the T3 conjugate for binding to the anti-T3 antibody.
At the end of the incubation period anti-fluorescein coupled to a magnetic solid phase is added in excess. This rapidly and specifically binds to the free T3-antibody complex and is sedimented in a magnetic field.
After aspirating the liquid phase and washing the solid phase, a solution of the enzyme substrate, phenolphthalein monophosphate is added to the incubation cell and the each cell incubated at 37°C. After incubation the enzyme reaction is stopped by the addition of a stop reagent and the intensity of the color developed is measured photometrically.The intensity of the color developed is inversely proportional, within the working range of the assay, to the concentration of free T3 in the sample. The concentration of free T3 in a patient sample or control is then determined by interpolation from a stored standard curve.
Eclectica Free T3 Reagent Kit
Eclectica Free T3 Calibration Kit
Eclectica Immunoassay Common Reagents Kit
Eclectica Immunoassay Wash Solution
Eclectica Systemic Wash Solution
1700006 Eclectica Cleaning Kit