Chromogranin A ELISA

INTENDED USE

The Calbiotech Chromogranin A ELISA (enzyme-linked immunosorbent assay) kit is intended for the quantitative determination of human Chromogranin A levels in human serum or plasma.

Summary and explanation

Chromogranin A (CgA) is a 49 KD glycoprotein. Elevated levels of CgA are used to differentiate between neuroendocrine and non-neuroendocrine tumors. About 50% of neuroendocrine tumors have elevated concentration of CgA. Serum CgA is most frequently elevated in gastrinoma (100%), pheochromocytoma (89%), carcinoid tumors (80%), nonfunctioning tumors of the endocrine pancreas (69%) and medullary carcinoma of the thyroid (50%). Only 7% of control subjects have elevated CgA and only 2% have extremely elevated serum CgA (>300 ng/ml).

PRINCIPLE OF THE TEST

The CgA is a solid phase direct sandwich ELISA method. The standards, samples and controls are added into the selected wells coated with anti hCgA monoclonal anybody. CgA in the standards, controls and patient’s serum binds to anti-CgA Ab on the wells. Unbound protein is washed off by wash buffer. The anti-hCgA-HRP conjugated second antibody is added and then binds to CgA. Unbound HRP conjugate is washed off by wash buffer. Upon the addition of the substrate, the enzyme activities are proportional to the concentration of CgA in the samples. A standard curve is prepared relating color intensity to the concentration of the CgA.