[Chromogranin A in blood--a useful tumor marker]

Chromogranin A (CgA) is a protein localized to the secretory granules of neuroendocrine cells. Determination of CgA in blood is a useful marker for neoplasia and hyperplasia of neuroendocrine cells. Chromogranin A in serum should be the first test used for detecting carcinoids. It is also useful for diagnosing other neuroendocrine tumours, such as oat-cell carcinoma of the lung, pheochromocytoma and neuroblastoma.