How is it used?When is it ordered?What does the test result mean?Is there anything else I should know?
The Chromogranin A test is used as a
tumor marker. It may be ordered in combination with or in place of
5-HIAA to help diagnose
carcinoid tumors. It is also used to help monitor the effectiveness of treatment and detect recurrence of this tumor. Sometimes it may be ordered with specific hormones, such as
catecholamines, to help diagnose and monitor a
pheochromocytoma. It may also be used to detect the presence of other
neuroendocrine tumors, even those that do not secrete hormones.
CgA is ordered along with other tests when a doctor suspects that a patient has a
carcinoid tumor,
pheochromocytoma, or other
neuroendocrine tumor. It may be ordered periodically to help evaluate treatment effectiveness and monitor for tumor recurrence.
What does the test result mean?NOTE: This test has no single number that identifies an abnormal result.
Your lab report (see a sample report) should include
a range of numbers (reference range) that identifies what is expected for you based on
your age, sex, and the method used in that laboratory. You can find more information
about expected results at Reference Ranges
and What They Mean. Lab Tests Online strongly recommends that you discuss the meaning of your test results with your doctor.
Chromogranin A concentrations are normally low. Increased levels in a symptomatic patient may indicate the presence of a tumor 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 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 patient may have a recurrence of the tumor.
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 levels should be considered when interpreting test results.
There are currently not any FDA approved Chromogranin A tests. 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.
