Special remarks:

PRINCIPLE OF THE TEST
The DEMEDITEC CYFRA 21-1 ELISA Kit is a solid phase enzyme-linked immunosorbent assay (ELISA) based on the sandwich principle. 
The microtiter wells are coated with a monoclonal [mouse] antibody directed towards a unique antigenic site of the CYFRA21-1 molecule. 
An aliquot of patient sample containing endogenous CYFRA21-1  is incubated in the coated well with enzyme conjugate, which is an anti- CYFRA21-1  monoclonal antibody conjugated with horseradish peroxidase. After incubation the unbound conjugate is washed off. 
The amount of bound peroxidase is proportional to the concentration of CYFRA21-1 in the sample. 
Having added the substrate solution, the intensity of colour developed is proportional to the concentration of CYFRA21-1 in the patient sample.

Summary and Explanation
CYFRA 21-1 is a fragment of cytokeratin 19. Although expressed in all body tissues its major occurrence is in the lung, particulary in lung cancer tissues. The major diagnostic importance of CYFRA 21-1 as a tumor marker is in differential diagnosis, prognosis, and aftercare of non-small-cell lung cancer (NSCLC) patients.
Additionally, CYFRA 21-1 has been described as a tumor marker for the monitoring of bladder cancer.   
The CYFRA 21-1 ELISA uses the two mouse monoclonal antibodies KS19.1 and BM19.21 to determine cytokeratin 19 fragments.