Serum chromogranin A measurement is used to monitor patients with cancer and 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 colorectal tumors, thyroid carcinoma, some gastrointestinal neoplasms as well as pituitary adenomas and possibly advanced prostate cancer.
Chromogranin A (CGA) is a 48-60 kD secretory molecular protein produced by neuroendocrine cells. The physiological role of chromogranin A has not been fully elucidated, but it has been hypothesized that it may serve as a precursor for other biologically active peptides or may serve other functions in the intracellular production of hormones and neuropeptides.
Chromogranin A has been used as an indicator of immunohistochemistry for normal and neoplastic neuroendocrine tissues. High plasma concentrations of chromogranin A have been shown in patients with endocrine tumors and, moreover, its blood concentration is correlated with tumor size. Several studies indicate that the measurement of 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 (eg hormones), also referred to as "non-functional tumors", can sometimes be detected because they retain the ability to secrete chromogranin A.
Chromogranin A is a more stable molecule than serotonin, making its measurement a useful alternative for the detection of carcinoid. Elevated levels of chromogranin A in patients with prostate cancer are associated with poor prognosis. Chromogranin A levels may be elevated in patients with severe renal failure and also often in patients treated with proton pump inhibitors.
Possible Interpretations of Pathological Values
- Increase: Carcinoid syndrome, pheochromocytoma, neuroblastoma, thyroid carcinoma, pituitary adenomas, small cell lung cancer, pancreatic islet cell tumors, APUDomas, neoplasms, APUDomas
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of 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 interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal 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 we contact your doctor to get the best possible medical care.