Chromogranin A

Test ID:

704786

CPT code:

86316

Clinical Use:

Detect neuroendocrine cancers

Test Information:

Human chromogranin A is 439-amino-acid protein with a molecular weight of 49 kilodaltons. It is a secretory protein that is produced by the dense-core vesicles of neuroendocrine cells. The physiologic role of this protein has not been fully elucidated, but it has been hypothesized that it may serve as a precursor to other biologically active peptides or may serve a function in the intracellular production of hormones and neuropeptides. Chromogranin A has been used as an immunohistochemical marker for normal and neoplastic neuroendocrine tissues. Elevated plasma concentrations have been demonstrated in patients with tumors of endocrine origin and levels have been shown to correlate with tumor volume. Several studies suggest that measurement of plasma chromogranin A may be a valuable diagnostic in subjects with tumors such as pheochromocytoma, carcinoid tumor, neuroblastoma, and small cell lung carcinoma. Neuroendocrine tumors that secrete no other hormone markers, referred to as “nonfunctioning” tumors, can sometimes be detected serologically because they retain the ability to secrete chromogranin A. Chromogranin A is more stable than serotonin, making its measurement a useful alternative for the detection of carcinoid tumor. Elevated levels of chromogranin A in patients with prostate cancer have been shown to correlate with poor prognosis.