Chromogranin A, Plasma

Definition

Chromogranin, also known as CGA and parathyroid secretory protein 1, is a member of the chromogranin/secretogranin (granins) family of neuroendocrine secretory proteins. It is a precursor to several functional peptides, including vasostatin, pancreastatin, catestatin, and parastatin. These peptides negatively modulate the neuroendocrine function of the releasing cell (autocrine) or nearby cells (paracrine). Chromogranin A is cleaved by an endogenous prohormone convertase to produce several peptide fragments. Peptides derived from chromogranin A with uncertain function include chromostatin, WE-14, and GE-25. The method of measurement is EIA.
Normal range: 0 " “50 ng/mL.

As an indicator for pancreas and prostate cancer
Aid in diagnosis of functioning neuroendocrine tumors; predicts response to treatment
Aid in diagnosis of nonfunctioning neuroendocrine tumors (e.g., thyroid carcinoma, small cell lung cancer, anterior pituitary adenoma)

Functioning neuroendocrine tumors and hyperplasia
Pheochromocytoma, aortic, and carotid body tumors
Neural tumors (e.g., neuroblastoma, ganglioneuroma, paraganglioma, medulloblastoma)
Carcinoid tumors in various locations
Gastroenteropancreatic tumors (e.g., gastrinoma, insulinoma, VIPoma)
Parathyroid adenoma, carcinoma, hyperplasia
Thyroid medullary carcinoma, hyperplasia
Tumors with variable neuroendocrine differentiation (e.g., breast, prostate) " ”low sensitivity
DM, kidney, liver, or heart failure; correlates with severity of the CHF

Tumors with possible neuroendocrine lineage (e.g., choriocarcinoma, thymoma, malignant melanoma, renal cell carcinoma)
After adrenal-to-caudate autografting and schizophrenia

Chromogranin A may not distinguish neuroendocrine hyperplasia from tumor.
EIA may have lower limit of detection than RIA. Results obtained with different assay methods or kits cannot be used interchangeably.