Chromogranin A, Serum

This test is performed using the BRAHMS CGA II Kryptor kit. Results obtained with different methods or kits cannot be used interchangeably. Results cannot be interpreted as absolute evidence of the presence or absence of malignant disease and should be evaluated in combination with clinical symptoms, diagnostic evidence, and/or other laboratory parameters. The change ofCgA concentration over time provides diagnostic information whether a tumor progression has occurred.

An increase of CgA serum concentrations of more than 50% to avalue of greater than 100 ng/ml between consecutive monitoring visits defines a positive test result, representing a higher probability that a tumor progression has occurred.

A change of CgA serum concentrations of equal or less than 50% increase between monitoring visits or to a value of 100 ng/ml or less defines a negative test result, representing a lower probability that a tumor progression has occurred.  Nontumor related elevations of Chromogranin A can be observed in gastrointestinal, cardiovascular, and renal disorders, cancers other than neuroendocrine tumors, as well as with proton pump inhibitor (PPI) therapy. It is recommended to stop PPI treatment for at least 14 days prior to testing.