Also Known As
CgA
Formal Name
Chromogranin A
This article was last reviewed on
This article waslast modified on
19 June 2018.
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.

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you will be able to access your results online.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, gender, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

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.

Accordion Title
Common Questions
  • How is it used?

    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.

  • When is it requested?

    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.

  • What does the test result mean?

    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.

  • Is there anything else I should know?

    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.

  • Should everyone have a Chromogranin A test?

    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.

  • How does a doctor locate the carcinoid or neuroendocrine tumour?

    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.

  • How does the doctor tell whether a tumour is benign or cancerous?

    They need to perform a biopsy or remove the tumour surgically and look at the tumour cells under the microscope.