A blood tumor marker used for detection of certain cancers. Chromogranin A is considered the best general neuroendocrine serum or plasma marker available both for diagnosis and therapeutic evaluation and is increased in 50-100% of patients with various neuroendocrine tumors. Chromogranin A serum or plasma levels reflect tumor load, and it may be an independent marker of prognosis in patients with midgut carcinoids. The measurement of CgA is considered “the gold standard” of chemical tests for confirming the diagnosis of carcinoid and neuroendocrine tumors and following their course.
