The measurement of serum chromogranin A is used to monitor patients with carcinoid tumors as well as to monitor their treatment, as a complementary test for the diagnosis of carcinoid tumors, as a complementary test for the diagnosis of other neuroendocrine tumors, including pheochromocytoma, medullary thyroid carcinoma, certain gastrointestinal neoplasms as well as pituitary adenomas and possibly advanced prostate cancer.
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Chromogranin A (CGA) is a secretory protein of molecular weight 48-60 kD produced by neuroendocrine cells. The physiological role of chromogranin A has not been fully elucidated. Still, it has been hypothesized that it may serve as a precursor for other biologically active peptides or serve different functions during the intracellular production of hormones and neuropeptides.
Chromogranin A has been used as an immunohistochemical marker for normal and neoplastic neuroendocrine tissues. High plasma concentrations of chromogranin A have been shown in patients with endocrine tumors, and its concentration in the blood correlates with tumor size. Several studies suggest that measuring chromogranin A can be a valuable diagnostic tool in patients with tumors such as pheochromocytoma, carcinoid, neuroblastoma, and small-cell lung cancer. Neuroendocrine tumors that do not secrete other markers (e.g., hormones), also called “nonfunctioning tumors,” can sometimes be detected because they retain the ability to secrete chromogranin A.
Chromogranin A is more stable than serotonin, making its measurement a helpful alternative for detecting carcinoids. Elevated chromogranin A levels in patients with prostate cancer are associated with a poor prognosis. Chromogranin A levels may be elevated in patients with severe renal insufficiency and are also commonly seen in patients treated with proton pump inhibitors.
Possible Interpretations of Pathological Values
- Increase: Carcinoid syndrome, pheochromocytoma, neuroblastoma, medullary thyroid carcinoma, pituitary adenomas, small cell lung cancer, pancreatic islet cell tumors, APUDomas, neuroendocrine tumors, prostate cancer, chronic renal failure. Medications: Proton pump inhibitors
Important Note
Laboratory test results are the most critical parameter for diagnosing and monitoring all pathological conditions. Between 70 to 80% of diagnostic decisions are based on laboratory tests. Correctly interpreting laboratory results allows a doctor to distinguish "healthy" from "diseased."
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be analyzed based on each case and family history, clinical findings, and the results of other laboratory tests and information. Your physician should explain the importance of your test results.
At Diagnostiki Athinon, we answer any questions you may have about the test you perform in our laboratory and contact your doctor to ensure you receive the best possible medical care.
