T-4 Free, 96 Wells

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T-4 Free, 96 Wells

Manufacturer: DRG International Inc.
Model: T-4 free, 96 Wells
Product Code: EIA-2386

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Block Scientific, a leading laboratory equipment supplier provides the T-4 free, 96 Wells at an affordable price. Our goal as one of the leading names in the industry, is to provide our customers with the right lab equipment for their preferred applications. Search our stock of new and refurbished laboratory equipment from all brand name manufacturers.

T-4 Free

– Solid Phase Assay

This product is a solid phase competitive enzyme immunoassay. It is useful for the quantitative determination of Free Thyroxine (fT4) concentration in Human serum.


L-Thyroxine (T4) or 3,5,3’,5’-tetraiodothyronine is the most commonly measured thyroid hormone for the diagnosis of thyroid function. T4 has its primary infuence on protein synthesis and oxygen consumption in virtually all tissues but it is also important for growth, development, and sexual maturation.

T4 is synthesized by the thyroid gland and is secreted into the bloodstream. Here the T4 becomes bound to serum proteins for transport to the cells. The major transport protein is Thyroxine Binding Globulin (TBG) which normally accounts for 80% of the bound T4. Other thyroid hormone binding proteins are Thyroxine Binding Prealbumin and Albumin. Most of the serum T4 is bound to these transport proteins leaving only about 0.03% free to exert its effect on cells. It is the free T4 (fT4) that represents the metabolically active fraction; for this reason the measurement of fT4 concentration is considered to be an indicator of patient thyroid status.

Primary hypothyroidism results in underproduction of T4 by the thyroid gland and consequently an abnormally low circulating fT4 concentration in the blood. Primary hyperthyroidism leads to excessive thyroid production on T4 and resulting elevated fT4 concentration.

Total serum T4 concentrations are dependent on the level of circulating TBG as well as the patient’s thyroid status.

The concentration of TBG can be affected by certain drugs, steriod hormones, pregnancy, and by various nonthyroid illnesses. In an earlier generation of thyroid function tests, the effect of variable TBG concentration was dealt with by calculating a Free Thyroxine Index (FTI). This FTI is the product of Total T4 concentration and Thyroid Uptake (TU), which assesses the number of available binding sites on the TBG. This approach requires carrying out two separate assay determinations (total T4 and TU), but does provide a better indicator of thyroid status than total T4 alone.

fT4 tests are designed to directly reflect the equilibrium existing in serum between T4 and TGB-bound T4. These methods, including this fT4 test, can generally reflect thyroid status in a single assay.




  • Materials provided with kit – fT4-Enzyme Conjugate Reagent, ready to use (1 vial, 10.5 ml); Antibody Coated Microplate (1 plate, 96 wells), Free T4 Reference Standard Set (1.0 ml/vial), color reagent B (1 bottle, 13 ml), Color Reagent A (1 bottle, 13 ml), stop solution (3N HCL) (1 bottle, 10 ml)
  • Storage – Unopened test kits can be stored at 2°C – 8°C upon receipt

For more information on T-4 free, 96 Wells and the range of other hormone assays that we carry, visit our online store. We are available on phone at 631-589-1118 or by e-mail at info@blockscientific.com.