Test
Chromogranin A
Other Test Request Name
CgA
Test Composition
Not Applicable
Intended Use
To help diagnose and monitor carcinoid tumors and other neuroendocrine tumors
Proteins present in the secretory chromaffin granules of neuroendocrine cells. Very high levels associated with neuroendocrine tumors and pheochromocytoma, intestinal carcinoid and tumors of the endocrine pancreas
Chromogranin A (CgA) is a protein released from neuroendocrine cells. These are cells that secrete hormones in response to signals from the nervous system. They are found in organs throughout the body. This test measures the amount of chromogranin A in the blood.
Neuroendocrine cells, and the endocrine glands that they are found in, can give rise to a variety of tumors, both benign and malignan. Examples include carcinoid tumors, insulinomas, small cell lung cancers, and neuroblastomas. The CgA test may be used to help detect, diagnose, and/or monitor neuroendocrine tumors, especially carcinoid tumors.
Many of these tumors release large quantities of the hormone associated with that tissue, either continuously or intermittently, causing symptoms characteristic for that tumor. However, not all neuroendocrine tumors release the expected hormones. In either case, neuroendocrine tumors are frequently associated with increased concentrations of CgA.
Carcinoid tumors are slow-growing noncancerous or cancerous masses that form mainly in the gastrointestinal tract (especially in the appendix) and in the lungs. According to the American Cancer Society, there are about 8,000 gastrointestinal and 4,000 lung carcinoid tumors diagnosed each year in the United States. Many more of these tumors may exist, but most remain small and do not cause any symptoms. When carcinoid tumors are discovered in asymptomatic patients during surgical procedures performed for other reasons, they are called "incidental" tumors. A small percentage of these tumors may eventually grow large enough to cause obstructions in the intestines or bronchial tubes of the lungs.
Methodology
Enzyme Immunoassay (EIA)
Laboratory Section
Special Test
Special Instructions/Patient Preparations
- No patient preparation necessary.
- PPIs (proton pump inhibitors) should be stopped 2-3 weeks before the chromogranin A assay
Collection/Sample Container
Red or Gold Tube
Specimen and Volume Requirement
Note:Follow tube manufacturer recommendation.
3 mL Serum
Alternative Specimen and Volume Requirement
Not Applicable
Specimen Stability
• Room Temperature (15-25°C)
24 Hours
• Refrigerated Temperature (2-8°C)
7 Days
• Freezer Temperature (-20°C)
28 Days
Transport Temperature
Transport specimen at 2°C - 8°C (with cold packs)
Rejection Criteria
- Hemolyzed specimen
- Quantity Not sufficient
- Markedly lipemic sample
- Improperly labeled specimen
Running Day
Batch running
Cut Off Time
Friday, 4:00 PM
TAT/Releasing of Results
2 weeks after cut-off (excluding Saturdays, Sundays and Holidays)
Reference Interval/Result Interpretation
Available upon request
Limitations/Interferences
None Specified
Frequently Asked Questions (FAQs)
Q: When to get tested?
A:When you have symptoms suggestive of a carcinoid tumor, such as flushing, diarrhea, and/or wheezing; when your healthcare provider thinks that you may have a carcinoid or other neuroendocrine tumor.
Q: When it is ordered?
A:A CgA test is ordered along with other tests when a healthcare practitioner suspects that a person's signs and symptoms are due to a carcinoid tumor or other neuroendocrine tumor.
Some signs and symptoms may include:
- Flushing of the face and neck (appearance of deep red color, usually with sudden onset)
- Diarrhea, nausea, vomiting
- Rapid heart rate
- Wheezing, coughing, difficulty breathing
This test may be ordered periodically to help evaluate treatment effectiveness and monitor for tumor recurrence.
Related Words/Test
autoantigen in type 1 diabetes, Serotonine, 5-HIAA, Catecholamines, Tumor Marker