Chromogranin "A" is a protein, located in neuroendocrine cells, which is co-secreted with a wide variety of peptide hormones and neurotransmitters. Tumours with neuroendocrine properties typically secrete large quantities of CgA into the circulation. The assay is used primarily in the diagnosis and monitoring of patients with carcinoid tumours, islet cell tumours, pheochromocytoma, neuroblastoma, and other tumours of neuroendocrine origin. It may also be used for small-cell lung cancer and prostate cancer, in men with normal PSA levels.
Non-malignant elevations may be seen in kidney, liver, or heart failure, It may also be elevated in patients experiencing significant stress because CgA is co-released with catecholamines.
CgA is measured using the DAKO ELISA double antibody sandwich assay. The required sample is 1ml serum. Aliquots should be shipped refrigerated or frozen. Prior to shipping the serum can be kept refrigerated for up to one week, and frozen for 6-12 months.
Testing is performed monthly, but frequency may increase, depending on test volumes and clinical circumstances.
Reference Range: <40 U/L