Chromogranin A

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Also known as: CgA
Formal name: Chromogranin A

At a Glance

Why Get Tested?

To help diagnose and monitor carcinoid tumours and other neuroendocrine tumours

When to Get Tested?

When you have symptoms suggestive of a carcinoid tumour such as flushing, diarrhoea, and/or wheezing. When your doctor thinks you may have a carcinoid or other neuroendocrine tumour

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

You may be required to fast overnight prior to the specimen being taken and to temporarily discontinue certain medication beforehand. Please check the local laboratory instructions with your doctor prior to blood being taken.

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. Neuroendocrine cells, and the endocrine system glands that they are found in, can give rise to a variety of tumours, both benign and malignant. They include carcinoid tumours, phaeochromocytomas, insulinomas, small cell lung cancers, neuroblastomas, and other neuroendocrine tumours. Many of these tumours release large quantities of hormones - such as serotonin, catecholamines, or insulin – continuously or intermittently, causing symptoms characteristic for that tumour. However, some neuroendocrine tumours do not release the expected hormones. In either case, neuroendocrine tumours are frequently associated with increased concentrations of CgA.

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?

You may be required to fast overnight prior to the specimen being taken and to temporarily discontinue certain medication beforehand. Please check the local laboratory instructions with your doctor prior to blood being taken.

The Test

Common Questions

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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.