Free Triiodothyronine (fT3) ELISA


The Free Triiodothyronine (fT3) ELISA Assay Kit (enzyme-linked immunoassay kit) is intended for the direct quantitative determination of free triiodothyronine in human serum. The Free Triiodothyronine (fT3) ELISA Assay Kit is for research use only and not to be used in diagnostic procedures.

SKU: T3F31-K01 Categories: , ,

Free Triiodothyronine (fT3) ELISA

Free Triiodothyronine (fT3) ELISA is For Research Use Only

Size: 1×96 wells
Sensitivity: 0.3 pg/mL
Dynamic Range: 2–40 pg/mL
Incubation Time: 75 minutes
Sample Type: Serum
Sample Size: 25 µL
Controls Included

Assay Principle

The principle of the Free Triiodothyronine ELISA Kit enzyme immunoassay test follows the typical competitive binding scenario. Competition occurs between an unlabeled antigen (present in standards, controls and patient samples) and an enzyme-labelled antigen (conjugate) for a limited number of antibody binding sites on the microplate. The washing and decanting procedures remove unbound materials. After the washing step, the enzyme substrate is added. The enzymatic reaction is terminated by addition of the stopping solution. The absorbance is measured on a microtiter plate reader. The intensity of the color formed is inversely proportional to the concentration of fT3 in the sample. A set of standards is used to plot a standard curve from which the amount of fT3 in patient samples and controls can be directly read. The labelled T3 (conjugate) employed in this assay system has shown no substantial binding properties towards thyroxine-binding globulin (TBG) or human serum albumin (HSA). The binding sites on the microplates are designed to be of a low binding-capacity in order not to disturb the equilibrium between T3 and its carrying proteins. The assay is carried out under normal physiological conditions of pH, temperature and ionic strength.

Approximately 0.1 mL of serum is required per duplicate determination. Collect 4–5 mL of blood into an appropriately labelled tube and allow it to clot. Centrifuge and carefully remove the serum layer. Store at 4°C for up to 24 hours or at -10°C or lower if the analyses are to be done at a later date. Consider all human specimens as possible biohazardous materials and take appropriate precautions when handling.

Related Products

Triiodothyronine T3 ELISA Assay Kit
Reverse T3 (rT3) ELISA Assay Kit
Free Thyroxine (fT4) ELISA Assay Kit

Additional Information

Assay Background

Triiodothyronine (T3) is a thyroid hormone found circulating in the bloodstream. T3 contains three iodine atoms and is produced largely through the extrathyroidal conversion of thyroxine (T4), the principal thyroid hormone with four iodine atoms. Most of the T3 that circulates in the blood is bound to carrier proteins such as TBG, pre-albumin and albumin. The free fraction of T3 (fT3), which represents only 0.25% of the total amount, is considered to be the physiological active fraction. Total T3 levels depend not only on thyroid status and the peripheral conversion of T4 to T3, but also on the concentration of thyroid hormone-binding proteins. Free T3 (fT3) on the other hand, is largely unaffected by variations in these carrier proteins which can occur under conditions such as pregnancy, estrogen therapy and the use of oral contraceptives. Therefore, free T3 typically reflects a patient’s actual thyroid status more reliably than total T3. Measurement of free T3 is generally recommended for patients with symptoms of hyperthyroidism as found in Graves’ disease, toxic adenoma and toxic multinodular goiter.

Typical Standard Curve

Package Inserts

Please note: All documents above are for reference use only and should not be used in place of the documents included with this physical product. If digital copies are needed, please contact us.

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