Thyroxine, Free, Human, BioAssay(TM) ELISA Kit (T4)

The United States Biological Thyroxine, Free, Human, BioAssay(TM) ELISA Kit is for the quantitative determination of free thyroxine concentration in human serum.\n\nBackground:\nThyroxine, the principal thyroid hormone, circulates in blood almost completely bound to carrier proteins. The main carrier is thyroxine-binding globulin (TBG). However, only the free (unbound) portion of thyroxine is responsible for the biological action. Further, the concentrations of the carrier proteins are altered in many clinical conditions, such as pregnancy. In normal thyroid function as the concentrations of the carrier proteins alters, the total thyroxine level changes so that the free thyroxine concentration remains constant. The increase in total thyroxine associated with pregnancy, oral contraceptives and estrogen therapy occasionally result in total T4 levels over the limits of normal while the free thyroxine concentration remains in the normal reference range. Masking of abnormal thyroid function can also occur in both hyper and hypothyroid conditions by alterations in the TBG concentration. The total T4 can be elevated or lowered by TBG changes such that the normal reference levels result. \nIn this method, serum reference, a control is first added to a microplate well. Enzyme-T4 conjugate (analog method) is added and the reactants are mixed. A competition reaction results between the enzyme conjugate and the free thyroxine for a limited number of antibody combining sites immobilized on the well. After the completion of the required incubation period, the antibody bound enzyme-thyroxine conjugate is separated from the unbound enzyme-thyroxine conjugate via a wash step. The activity of the enzyme present on the surface of the well is quantitated by reaction with a suitable substrate to produce color. The employment of several serum references of known free thyroxine concentration permits construction of a graph of activity and concentration. From comparison to the dose response curve, an unknown specimen's activity can be correlated with free thyroxine concentration.\n \nKit Components: \n1. Serum References: 6x1ml \n2. fT4 (HRP) Reagent: 1x13ml\n3. Microtiter Plate: 1x96 wells\n4. Wash Solution Concentrate: 1x20ml\n5. Tetramethylbenzidine (TMB) A: 1x7ml \n6. Tetramethylbenzidine (TMB) B: 1x7ml \n7. Stop Solution: 1x8ml (1N HCl) \n\nStorage and Stability:\nStore all components at 4 degrees C. Stable for 6 months. For maximum recovery of product, centrifuge the original vial prior to removing the cap.

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SPECIFICATIONS

Catalog Number

T5460-10B

Size

1Kit

Applications

ELISA

Reactivities

Hum

References

1. Barker, S.B., \"Determination of Protein Bound Iodine.\",Joumal Biological Chemistry 173, 175. (1948)2. Chopra, I.J., Solomon, D.H., and Ho, R.S., \"A Radioimmunoassay of Thyroxine\", J. Clinical EndocrinoL 33, 865. (1971) 3. Young, D.S., Pestaner, L.C., and Gilberman, U., \"Effects of Drugs on Clinical Laboratory Tests\", Clinical Chemistry 21, 3660. (1975). 4. Sterling, L., Diagnosis and Treatment of Thyroid Disease, Cleveland, CRC Press P. 19-51. (1975) 5. Halpern, E.P and Bordens, RW. \"Microencapsulated antibodies in radioimmunoassay. Determination of free Thyroxine\". Clinical Chemistry Vol. 25, 1561-1563. (1979)6. Stjernholm, MR, Alsever, RN and Rudolph, MC. \"Thyroid function tests in diphenylhydantoin-treated patients\". Clin. Chem. Vol. 21, 1388:1392. (1977) 7. Nelson J.C. and Wilcox, RB. \"Analytical performance of Free and Total thyroxine assays\". Clin. Chem. 42: 146-154. (1996) 8. Midgeley John, EM. \"Direct and Indirect Free Thyroxine Assay Methods. Theory and Practice\". Clin. Chem. 47: 1353-1363. (2001) 9. Bayer, MF and McDougall, IR. \"Radioimmunoassay of free thyroxine in serum: comparison with clinical findings and results of conventional thyroid-function tests\". Clin. Chem. 26: 1186-1192. (1980)10. Anthony, GW, Jackson, RA et.al. \"Misleading results from immunoassays of serum free thyroxine in the presence of rheumatoid factor\". Clin. Chem. Vol. 43, 957-962. (1997) 11. Wosilait, WD. \"A theoretical analysis of the distribution of thyroxine among sites on the thyroxine binding globulin, thyroid binding prealbumin and serum albumin\". Res. Comm. Chem. Pathology-Pharmacology 16: 541-548. (1977).