Chromogranin A is an established marker for neuroendocrine tumours. Chromogranin B has been shown to be a diagnostic tool with similar use and characteristics as chromogranin A. However, chromogranin A levels are often elevated in patients with decreased renal function, patients with atrophic gastritis and in patients on treatment with proton inhibitors, which can give undesired false positive answers. Chromogranin B levels are not affected by these factors. Chromogranin B measurement can therefore serve as a valuable complement to chromogranin A as an important marker for neuroendocrine tumours.
Principle of the assays
Chromogranin immunoreactivity in blood is stable in vitro and can be detected by the radioimmunoassay (RIA) technique.The chromogranin assays developed by Euro Diagnostica are competitive methods based on polyclonal antibodies raised in rabbits. For chromogranin A the antibodies were raised against a purified fragment containing amino acid sequence 116-439 and for chromogranin B the antibodies were raised against a synthetic peptide containing amino acid sequence 439-451. Both intact chromogranin and fragments are measured in the respective assay.« Back