SUMMARY AND EXPLANATION

T4 is a useful marker for the diagnosis of hypothyroidism and hyperthyroidism. The level of T4 is decreased in hypothyroid patients and is increased in hyperthyroid patients. The level of T4 is normal in Euthyroid individuals.

PRINCIPLE OF THE TEST

The CBI T4 is a solid phases competitive ELISA. The samples, assay buffer and T4 enzyme conjugate are added to the wells coated with anti-T4 monoclonal antibody. T4 in the patient’s serum competes with a T4 enzyme (HRP) conjugate for binding sites. Unbound T4 and T4 enzyme conjugate is washed off by washing buffer. Upon the addition of the substrate, the intensity of color is inversely proportional to the concentration of T4 in the samples. A standard curve is prepared relating color intensity to the concentration of the T4.