From the Guidelines
Chromogranin A (CgA) is a blood test that measures the level of chromogranin A protein in the bloodstream, primarily used to detect and monitor neuroendocrine tumors (NETs). This test is especially useful for diagnosing carcinoid tumors, pheochromocytomas, neuroblastomas, and pancreatic neuroendocrine tumors, as it can help detect elevated levels of CgA, which is produced and released by neuroendocrine cells, particularly when they form tumors 1. The test works by detecting these elevated levels, making it a valuable tool for monitoring treatment response and detecting recurrence in patients with known NETs. Some key points to consider when interpreting results include:
- Certain medications, such as proton pump inhibitors like omeprazole, can cause false elevations in CgA levels 1
- Kidney failure, heart failure, and inflammatory conditions can also cause false elevations in CgA levels 1
- For accurate results, patients should stop taking proton pump inhibitors for at least two weeks before testing if possible 1
- The test requires a simple blood draw and is relatively non-invasive compared to tissue biopsies, making it a valuable screening and monitoring tool for neuroendocrine tumors 1 It's also important to note that chromogranin A levels can be used as a tumor marker, although not diagnostic, elevated levels have been associated with recurrence 1. Additionally, an analysis of a large prospective database showed that chromogranin A levels elevated twice the normal limit or higher were associated with shorter survival times for patients with metastatic NETs 1. Overall, the chromogranin A test is a useful tool for detecting and monitoring neuroendocrine tumors, and its results should be interpreted in the context of the patient's overall clinical picture.
From the Research
What is Chromogranin A Test
- Chromogranin A (CgA) is a protein that is widely used as a biomarker for neuroendocrine tumors, including pheochromocytoma and paraganglioma 2, 3, 4, 5, 6
- The test measures the level of CgA in the blood, which can be elevated in patients with these types of tumors
Diagnostic Use
- CgA is a sensitive marker for the diagnosis of pheochromocytoma, with elevated levels found in 86.9% to 97.1% of patients 2, 4, 6
- It is also useful in the diagnosis of paraganglioma, particularly in non-functional cases where other biochemical markers may not be elevated 4
- However, the test has limitations, including a lack of standardization and the potential for false positives due to other conditions that can elevate CgA levels 5
Prognostic Use
- Elevated CgA levels have been associated with a poorer outcome in patients with advanced neuroendocrine neoplasms 5
- However, the use of CgA as a prognostic marker is still limited, and more research is needed to fully understand its potential in this area