Calbiotech FT4 Elisa Kit - Thryoxine, Free

Product Description

PRINCIPLE OF THE TEST
The CBI fT4 is a solid phase competitive ELISA. The samples Anti-T4 Biotin and fT4 enzyme conjugateare added to the wells coated with Streptavidin. fT4 in the patient™s serum competes with a T4 enzymeconjugate for binding sites. Unbound T4 and T4 enzyme conjugate is washed off by washing buffer. Uponthe addition of the substrate, the intensity of color is inversely proportional to the concentration of fT4 in thesamples. A standard curve is prepared relating color intensity to the concentration of the fT4. 

SUMMARY AND EXPLANATION
Over 99% of thyroxine (T4) circulates in blood is bound to carrier proteins; 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 aspregnancy. In normal thyroid function as the concentrations of the carrier proteins alters, the total T4 levelchanges so that the free T4 concentration remains constant. Thus, measurements of free T4concentrations correlate more reliably with clinical status than total T4 levels. The increase in total T4levels associated with pregnancy, oral contraceptives and estrogen therapy result in higher total T4 levelswhile the free T4 concentration remains basically unchanged.