Chromogranin A, Plasma

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Subject: Chromogranin A, Plasma

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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.

Use

  • 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)

Interpretation

Disorders with Increased Values

  • 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

Disorders without Increased Values

  • Tumors with possible neuroendocrine lineage (e.g., choriocarcinoma, thymoma, malignant melanoma, renal cell carcinoma)

  • After adrenal-to-caudate autografting and schizophrenia

Disorders with Decreased Values

  • CSF in Parkinson disease

Limitations

  • 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.

 
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