At a Glance
Why Get Tested?
When to Get Tested?
When you have symptoms suggestive of a carcinoid tumor such as flushing, diarrhea, and/or wheezing; when your doctor thinks that you may have a carcinoid or other neuroendocrine tumor
A blood sample drawn from a vein in your arm
Test Preparation Needed?
Fasting may be required; follow any instructions from your doctor or laboratory
The Test Sample
What is being tested?
This test measures the amount of Chromogranin A (CgA) in the blood. CgA is a protein found in and released from neuroendocrine cells. These are cells that are found in organs throughout the body and that have both nerve and endocrine aspects. Neuroendocrine cells, and the endocrine system glands that they are found in, can give rise to a variety of tumors, both benign and malignant. They include carcinoid tumors, pheochromocytomas, insulinomas, small cell lung cancers, neuroblastomas, and other neuroendocrine tumors. Many of these tumors release large quantities of hormones, such as serotonin, catecholamines, or insulin, continuously or intermittently, causing symptoms characteristic for that tumor. However, some neuroendocrine tumors do not release the expected hormones. In either case, neuroendocrine tumors are frequently associated with increased concentrations of CgA.
According to the American Cancer Society, there are about 11,000 to 12,000 neuroendocrine tumors or cancers 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.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation may be needed or fasting may be required. Follow any instructions from the doctor or laboratory.
Ask a Laboratory Scientist
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
(© 1995-2010). Unit Code 83559: Chromogranin A, Serum. Mayo Clinic, Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/83559 through http://www.mayomedicallaboratories.com. Accessed December 2010.
Grenache, D. (Updated 2010 August). Pancreatic Neuroendocrine Tumors – NET. ARUP Consult [On-line information]. PDF available for download at http://www.arupconsult.com/assets/print/NET.pdf through http://www.arupconsult.com. Accessed December 2010.
Frank, E. (Updated 2010 January). Carcinoid Tumors. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/CarcinoidTumors.html?client_ID=LTD through http://www.arupconsult.com. Accessed December 2010.
(Revised 2010 July 13). Detailed Guide, Gastrointestinal Carcinoid Tumors. American Cancer Society [On-line information]. Available online at http://www.cancer.org/Cancer/GastrointestinalCarcinoidTumor/DetailedGuide/index through http://www.cancer.org. Accessed December 2010.
(Revised 2010 August 17). Detailed Guide, Lung Carcinoid Tumors. American Cancer Society [On-line information]. Available online at http://www.cancer.org/Cancer/LungCarcinoidTumor/DetailedGuide/lung-carcinoid-tumor-what-is-lung-carcinoid-tumor through http://www.cancer.org. Accessed December 2010.
Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 871-873.
Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007, Pg 343.
(Updated Sept 1, 2010) Santacroce L, Diomede L, Lodovico B. Malignant Carcinoid Syndrome. eMedicine article. Available online at http://emedicine.medscape.com/article/282515-overview through http://emedicine.medscape.com. Accessed February 2011.
(Updated May 25, 2012) Elhomsy G, Staros EB. Chromogranin A. eMedicine article. Available online at http://emedicine.medscape.com/article/2114314-overview#aw2aab6b4 through http://emedicine.medscape.com. Accessed November 2012.
CarcinoidLink. Biochemical Monitoring for Patients: Chromogranin A (CgA) Testing. Available online through http://www.carcinoid.com. Accessed November 2012.
Sources Used in Previous Reviews
Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 262-263.
(2006 January 4, Revised). Tumor Markers. American Cancer Society [On-line information]. Accessed on: 11/1/07. Available online
(2007 May 11, Reviewed). Detailed Guide: Gastrointestinal Carcinoid Tumors. American Cancer Society [On-line information]. Available online at http://www.cancer.org/docroot/CRI/CRI_2_3x.asp?dt=14 through http://www.cancer.org. Accessed on 11/1/07.
Nanda, R. (2006 September 11). Carcinoid syndrome. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000347.htm. Accessed on 11/1/07.
(© 2007). Pheochromocytoma. ARUP Consult [On-line information]. Available online through http://www.arupconsult.com. Accessed on 11/1/07.
(© 2007). Chromogranin A. ARUP's Laboratory Test Directory [On-line information]. Available online at http://www.aruplab.com/guides/ug/tests/0080469.jsp through http://www.aruplab.com. Accessed on 11/1/07.
(© 2007). Multiple Endocrine Neoplasias MEN. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/EndocrineDz/MEN.html through http://www.arupconsult.com. Accessed on 11/1/07.
(© 2007). Chromogranin A. Labcorp Test Menu [On-line information]. Available online at http://www.labcorp.com/datasets/labcorp/html/chapter/ through http://www.labcorp.com. Accessed on 11/1/07.
Nanda, R. (September 11, 2006) Medline Plus Encyclopedia. Pheochromocytoma (Online information). Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000340.htm. Accessed November 2007.