Chromogranin A

Other names: CgA

Chromogranin A is a protein, which is released by the neuroendocrine cells. Neuroendocrine cells can contribute to benign and malignant tumours, including carcinoid tumours, insulinomas and phaeochromocytomas.

When is the test used?

The test is primarily used to diagnose carcinoid tumours but it may also be used for other types of neuroendocrine tumours and phaeochromocytomas. The test may be carried out alongside other tests, including specific hormone tests.

The test may be ordered when a patient has symptoms that are consistent with a carcinoid tumour, other types of neuroendocrine tumour or phaeochromocytomas.

The test may also be repeated once a patient has started a course of treatment to monitor their condition.

How is the test performed?

The test is done by collecting a sample of blood from the arm; a needle is inserted into a vein in the arm and the blood is drawn back and collected in a syringe. Once the sample has been collected, it will be bottled, labelled with the patient’s name and sent away to the laboratory for analysis.

What do the test results mean?

Levels of chromogranin A are usually very low so if the test results show increased concentration and the patient has symptoms, this usually indicates that they have a tumour. The test will not tell the doctor where the tumour is or what type of tumour it is. The amount of CgA does not determine the severity of the tumour, but it will give the doctor a guide to the mass of the tumour.

If the test shows that levels of CgA have fallen after a patient has had treatment, this indicates that the treatment is working. If levels begin to rise after the treatment is complete, this may mean that the tumour has come back.

Specific Blood Tests

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