Search our Test Catalog. Specify what to search (name, test code, titles, everywhere) and how to search (begins with, contains)

Unit Code 600915:
T3 (Triiodothyronine), Free and Total, Serum

Print Friendly View
Print Page Email Page

Method Description

The instrument used is a Beckman Coulter DXI 800. The Access

Total and Free T3 assays are competitive-binding immunoenzymatic

assays. For the total T3 assay, sample is added to a reaction

vessel with a stripping agent to dissociate T3 from the binding

proteins. T3 in the sample competes with the T3 analogue coupled

to biotin for anti-T3 alkaline Phosphatase conjugate. Of the resulting

antigen:antibody complexes, the T3 analogue:antibody complexes

are bound to the streptavidin-coated solid phase. Separation in

a magnetic field and washing removes the sample T3:antibody

complexes and other materials not bound to the solid phase.

 

For the FT3 assay, sample is added to a reaction vessel with mouse

monoclonal antitriiodothyronine (anti-T3) and paramagnetic particles

coated with goat antimouse capture antibody. During the first incubation,

free T3 in the sample reacts with the anti-T3 antibody and is subsequently

bound to the capture antibody. After incubation in a reaction vessel,

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

unbound materials are washed away. Next, T3-alkalinephosphatase

conjugate and buffer are added to the reaction vessel to react with

the remaining anti-T3 antibody binding sites. After incubation in a reaction

vessel, materials bound to the solid phase are held in a magnetic field,

while unbound materials are washed away. For both the total T3 and

the FT3 assays, 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 total and FT3 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, 2005)

Performing Laboratory Location

New England

Key