Free T4 RIA Kit

Name Free T4 RIA kit
Full name Human Free T4 RIA Test Kit
Category Name Thyroid RIA kits
Test 100
Principle Competitive Immunoradiometric assay
Detection Range 0-5.0 ng/dL
Sample 25 λ
Sensitivity 0.08 ng/dL
Total Time ~45 min
Shelf Life 45 Days from the manufacturing date

Free T4 RIA kit description:

The Diagnostic Automation Free T4 RIA is intended for the quantitative determination of the Free Thyroxine (T4) concentration in human serum.

Materials provided with Free T4 RIA Test Kit:

1. Coated Tubes: T4 Antigen (100 tubes)

2. Thyroxine(T4) antigen Labelled with I 125 (Tracer I125)

3. Free T4 standard set, contains 0, 0.4, 0.85, 1.9 ,5 ng/dL, ready for use

4. Control serum (1Vial, 0.5 ml)

Materials Required, not Provided:

1. Precision pipettes

2. Distilled or deionized water

3. Gama counter


Thyroxine is the main hormone of the thyroid. Most thyroxine in blood circulation is predominantly bound to the thyroxine binding globulin (TBG) and to a lesser extent to the thyroxine binding prealbumin and albumin. A very small percentage of thyroxine remains unbound in blood as free. These unbound fractions of the thyroid hormone are thought to be responsible for the biologic activity. The metabolic processes are regulated entirely by the concentration of the free thyroid hormones. As the concentrations of the carrier proteins alter, the total thyroxine level changes so that the free thyroxine concentration remains constant. Thus, measurement of free thyroxine concentrations correlates better with clinical status than total thyroxine levels. The changes in total thyroxine concentrations associated with pregnancy, Liver failure and kidney failure occasionally result in total T4 levels over the limits of normal while the free thyroxine concentration remains within the normal reference range. The total T4 can be elevated or lowered. The free T4 concentration shows the real state of thyroid function and measurement of this free T4 is very important.

Principle of the assay

Immune radiometric assay (IRMA) kit, evaluates FT4 based on the competitive sandwich reaction. The present free T4 in the samples compete with the calibrator to bind to the coated conjugated FT4 anti-serum onto the tube walls. The contents of the tubes are aspirated and then the bound activity is measured in a gamma counter. The amount of activity form in the tube has an inverse relationship to the FT4 concentration of the sample. FT4 standards with known concentrations are tested with the unknown samples in which the concentration of unknown samples is achieved based on the standard curve of the counted amount against concentration of FT4.