Chromogranin A
Note: this site is for informational purposes only. To view test results or book a test, use the NHS app in England or contact your GP.
A chromogranin A test measures the level of chromogranin A in a blood sample, a protein released by neuroendocrine cells. It is used to help detect and monitor neuroendocrine tumours, such as carcinoid tumours and other cancers arising from hormone-producing cells.
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.
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.
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.
Common questions
The Chromogranin A test is used as a tumour marker. It may be requested in combination with or in place of 5‑HIAA to help diagnose carcinoid tumours. It is also used to help monitor the effectiveness of treatment and detect recurrence of this tumour. Sometimes it may be requested with specific hormones, such as catecholamines, to help diagnose and monitor a phaeochromocytoma. It may also be used to detect the presence of other neuroendocrine tumours, even those that do not secrete hormones.
CgA is requested along with other tests when a doctor suspects that a patient has a carcinoid tumour, phaeochromocytoma, or other neuroendocrine tumour. It may be requested periodically to help evaluate treatment effectiveness and monitor for tumour recurrence.
Chromogranin A concentrations are normally low. Increased concentrations in a symptomatic patient may indicate the presence of a tumour but will not tell the doctor what type it is or where it is. The quantity of CgA is not associated with the severity of a patient’s symptoms but is associated with the tumour burden – the mass of the tumour.
If concentrations of CgA are elevated prior to treatment and then fall, then treatment is likely to have been effective. If following treatment of the tumour concentrations begin to rise again, then the patient may have a recurrence of the tumour.
When interpreting the result of chromogranin A blood test, caution is recommended, bearing in mind the multitude of factors that may lead to both false positive and negative results.
CgA concentrations may be elevated in other conditions, such as liver disease, inflammatory bowel disease, renal insufficiency, and with stress. These possible causes for elevated CgA concentrations should be considered when interpreting test results.
A variety of methods are available for measuring CgA. Those CgA tests that have been developed and validated by laboratories will all be slightly different and their results will not be interchangeable. For this reason, if a patient is having more than one CgA test performed (such as for monitoring) then his or her doctor will generally send each sample to the same laboratory.
No. This test is usually requested to help diagnose and monitor a carcinoid or other neuroendocrine tumour, both of which are uncommon. Most people will never need to have this test performed.
This is usually done through the use of imaging scans such as X‑rays, computed tomography (CT), magnetic resonance imaging (MRI) or nuclear medicine tests. In some cases, surgery is required to find the tumour.
They need to perform a biopsy or remove the tumour surgically and look at the tumour cells under the microscope.