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Unit Code 200154:
T4 (Thyroxine), Total Only, Serum

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Method Description

The instrument used is a Beckman Coulter UniCel DxI 800.

The Access Total T4 assay is a competitive-binding immno-

enzymatic assay. A sample is added to a reaction vessel with

antithyroxine antibody, thyroxine-alkaline phosphatase conjugate,

and paramagnetic particles coated with goat antimouse capture

antibody and a stripping agent to dissociate all T4 from binding

proteins. Thyroxine in the sample competes with the thyroxine-

alkaline phosphatase conjugate for binding sites on a limited

amount of specific antithyroxine antibody. Resulting antigen:

antibody complexes bind to the capture antibody on the solid

phase. After incubation in a reaction vessel, materials bound to

the solid phase are held in a magnetic field, while unbound materials

are washed away. The chemiluminescent substrate Lumi-Phos* 530

is added to the vessel and light generated by the reaction is measured

with a luminometer. The light production is inversely proportional to

the concentration of thyroxine in the sample. The amount of analyte

in the sample is determined from a stored, multipoint calibration curve.

(Package Insert: Beckman Coulter Ireland Inc. Ireland 2007)

Performing Laboratory Location

Rochester

Key