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Free Triiodothyronine
REF: DS177704 96 tests 

Intended use
Immunoassay for the in vitro quantitative determination of free triiodothyronine in human serum.

Triiodothyronine is one of the thyroid hormones present in serum which regulates metabolism. Determination of this hormone concentration is important for the diagnostic differentiation of euthyroid, hyperthyroid, and hypothyroid states. The major fraction of total triiodothyronine is bound to the transport proteins (TBG, prealbumin, albumin). Free triiodothyronine (fT3) is the physiologically active form of the thyroid hormone triiodothyronine (T3). The determination of free T3 has the advantage of being independent of changes in the concentrations and binding properties of the binding proteins; additional determination of a binding parameter (T-uptake, TBG) is therefore unnecessary. (1, 2, 3)In normal thyroid function, as the concentrations of the carrier proteins alter, the total T3 level changes so that the FT3 concentration remains constant. (4) Thus, 
measurements of FT3 concentrations correlate more reliably with clinical status than total T3 levels. For example, the increase in total T3 levels associated with pregnancy, oral contraceptives and estrogen therapy result in higher total T3 levels while the FT3 con- centration remains basically unchanged. (5) In addition, it has been found that the mean FT3 value has a gradient decreasing from young to older. (6)

Materials provided

• Coated Microplate, 8 x 12 strips, 96 wells, pre-coated with T3 derivant.
• Calibrators, 6 vials, 1 ml each, ready to use; Concentrations: 0(A), 2(B), 5(C), 10(D), 20(E) and 50(F) pmol/L.
• Enzyme Conjugate, 1 vial, 6.0 ml of HRP (horseradish peroxidase) labeled sheep monoclonal Anti-T3 in Tris-NaCl buffer containing BSA (bovine serum albumin). Contains 0.2% ProClin300 preservative.
• Substrate, 1 vial, 11ml, ready to use, (tetramethylbenzidine) TMB.
• Stop Solution, 1 vial, 6.0 ml of 1 mol/l sulfuric acid.
• Wash Solution Concentrate, 1 vial, 25 ml (40X concentrated), PBS-Tween wash solution.
• IFU, 1 copy.
• Plate Lid: 1 piece.

Materials required (but not provided)
• Microplate reader with 450nm and 620nm wavelength absorbent capability.
• Microplate washer. 
• Incubator.
• Plate shaker.
• Micropipettes and multichannel micropipettes delivering 50μl with a precision of better than 1.5%.
• Absorbent paper. 
• Distilled water.