Chromogranin A

Also Known As

CgA

This article was last reviewed on

December 17, 2015.

This article waslast modified on March 5, 2020.

At a Glance

Why Get Tested?

To help diagnose and monitor carcinoid tumors and other neuroendocrine tumors

When To Get Tested?

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

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

Fasting may be required; follow any instructions from your healthcare provider or laboratory.

You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

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 malignant. 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.

Common Questions

How is it used?

The chromogranin A (CgA) test is used as a tumor marker. It may be ordered in combination with a 5-HIAA test to help diagnose carcinoid tumors. It may also be used to detect the presence of other tumors arising from neuroendocrine cells.

Neuroendocrine cells are cells that have both nerve and hormone (endocrine) aspects and are found in organs throughout the body. These cells and the endocrine system glands that they are found in can give rise to a variety of tumors, both benign and malignant. Examples include carcinoid tumors, insulinomas, small cell lung cancers, and neuroblastomas.

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.

A CgA test may also be used to help monitor the effectiveness of treatment and detect recurrence of these tumors.
When is it ordered?
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.
What does the test result mean?

The level of chromogranin A in the blood is normally low. A person with no signs or symptoms and a normal level of CgA is unlikely to have a neuroendocrine tumor. However, the test is not perfect, and it is possible to have a neuroendocrine tumor even if the concentration of CgA is normal.

An increased CgA level in a person with symptoms may indicate the presence of a tumor, but it is not specific for the type of tumor or its location. In order to diagnose the condition, the tumor itself must be located, biopsied, and examined by a pathologist. The healthcare practitioner will frequently follow an abnormal test result with an order for an imaging scan to help locate any tumor(s) that may be present.

Not all patients with a neuroendocrine tumor have typical signs and symptoms. Some tumors do not produce the hormone associated with that tissue or only produce it intermittently.

The concentration of CgA is proportional to the tumor burden - the mass of the tumor. If concentrations of CgA are elevated prior to treatment and then fall, then treatment is likely to have been effective. If monitored levels begin to rise, then the person may have a recurrence of the tumor.
Is there anything else I should know?

CgA concentrations may be elevated in conditions such as liver disease, inflammatory bowel disease, renal insufficiency, and with stress. These possible causes for elevated CgA levels should be considered when interpreting test results. Chromogranin A can also be increased in people who take proton pump inhibitors (PPIs), which are drugs that reduce the amount of stomach acid.

There are currently no FDA-approved chromogranin A tests. Those CgA tests that have been developed and validated by laboratories are all slightly different, and their results are not interchangeable. When monitoring a patient over time, CgA tests should be performed by the same laboratory so that values can be compared.
Should everyone have a chromogranin A test?

No. This test is usually ordered to help diagnose and monitor a carcinoid or other neuroendocrine tumor, both of which are uncommon. Most people will never need to have this test performed.
How does a healthcare practitioner locate the carcinoid or neuroendocrine tumor?

This is usually accomplished through the use of imaging scans such as x-rays, computed tomography (CT), or magnetic resonance imaging (MRI). In some cases, surgery is required to find the tumor. For more on these imaging tests, visit RadiologyInfo.org.
How does the healthcare practitioner tell whether a tumor is benign or cancerous?

In order to determine whether the tumor is benign or cancerous, the healthcare practitioner will need to perform a biopsy or remove the tumor surgically. The tumor is sent to the laboratory, where a pathologist examines the tumor cells under the microscope and makes a diagnosis. (For more on this, read the article on Anatomic Pathology.)

See More Common Questions See Less Common Questions

View Sources

Sources Used in Current Review

Elhomsy, G. (2014 November 21, Updated). Chromogranin A. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/2114314-overview. Accessed 11/15/15.

(© 1995–2015). Chromogranin A, Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/34641. Accessed 11/15/15.

Frank, E. et. al. (2015 February, Updated). Carcinoid Tumors. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/CarcinoidTumors.html?client_ID=LTD. Accessed 11/15/15.

(2015 April 17, Revised). How are gastrointestinal carcinoid tumors diagnosed? American Cancer Society [On-line information]. Available online at http://www.cancer.org/cancer/gastrointestinalcarcinoidtumor/detailedguide/gastrointestinal-carcinoid-tumors-diagnosed. Accessed 11/15/15.

(2014 February). Monitoring Carcinoid Tumors and Pancreatic Neuroendocrine Tumors. Carcinoid for Health Care Professionals [On-line information]. Available online at http://www.carcinoid.com/health-care-professional/monitoring-carcinoid-tumors.jsp. Accessed 11/15/15.

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].

(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. 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.

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.

(© 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. 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. 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. 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. 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. Accessed December 2010.

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. 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. Accessed November 2012.

CarcinoidLink. Biochemical Monitoring for Patients: Chromogranin A (CgA) Testing. Available online through http://www.carcinoid.com. Accessed November 2012.

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