Chromogranin A

Has your doctor recommended chromogranin A, or are you being treated for a neuroendocrine tumour? This blood test helps monitor how the disease responds to treatment and whether it changes over time. It is not a test for a healthy person to check whether they have cancer, but one piece of information a doctor uses alongside imaging and other results.

Who the test is for

• people with a confirmed neuroendocrine tumour (NET) of the intestine, pancreas or lungs, to monitor the disease and treatment effect;
• after surgery or other NET treatment, as part of regular follow-ups;
• when a doctor suspects a NET because of symptoms such as episodes of facial and neck flushing, prolonged watery diarrhoea or wheezing;
• when CT, MRI or ultrasound has found a change about which a doctor wants additional information;
• sometimes in investigating other rare tumours of endocrine glands, alongside their main tests.

What the test reveals

Chromogranin A is a protein produced and released by neuroendocrine cells. These cells are scattered throughout the body, most abundantly in the digestive system, pancreas and lungs, and combine the nervous and hormonal systems. When a tumour arises from them, more chromogranin A than usual is often released into the blood.

The test is most useful for an already known tumour. If the value decreases during follow-ups, this usually accompanies a good treatment response, while a rise may warn of disease growth, prompting a doctor to decide on additional imaging. In diagnosis, chromogranin A is only supporting information: imaging and tissue analysis provide confirmation. A doctor may also request NSE, and you can read about the purpose of these tests in the article Tumour markers.

The procedure and preparation

A blood sample is taken from a vein, and the draw takes a few minutes. Fasting is not required.

Your medications matter. Medicines reducing stomach acid, particularly proton pump inhibitors (pantoprazole, omeprazole, esomeprazole and similar), can substantially raise chromogranin A and produce a falsely elevated result. Avoiding them for at least two weeks before the blood draw is therefore often advised, but only if approved by the doctor who prescribed them. If you must not stop the medicine, mention this at the blood draw and to the doctor interpreting the result.

Follow-ups are best performed at the same laboratory and with the same medications, because results from different methods cannot be compared directly.

What your result means

The normal limit depends on the method and is printed on your report. Your doctor interprets it alongside your symptoms, imaging, medicines and previous results.

• Normal result: does not rule out a neuroendocrine tumour, because small tumours and some tumour types do not raise chromogranin A. In a person receiving treatment, a consistently low value is usually a good sign.
• Mildly elevated result: is most often not a sign of a tumour. Common causes include stomach acid medicines, chronic inflammation of the stomach lining (atrophic gastritis), reduced kidney function, heart failure, liver disease and inflammatory bowel disease.
• Markedly elevated result: with appropriate symptoms or imaging findings, may suggest a neuroendocrine tumour, so a doctor plans further investigations.
• Change during follow-up: is more important than one result. A gradual rise with a known tumour is a reason to discuss additional tests with an oncologist or endocrinologist.

How to arrange testing

You can have blood taken without an appointment or referral at one of our branches across Croatia (listed under Contact). Prices for all tests and panels are available in the price list.

Frequently asked questions

Is chromogranin A a cancer test?

It is not a screening test. It is not recommended for healthy people without symptoms, because a mildly elevated result most often has a harmless cause and may lead to unnecessary concern and testing. It is used for a known or reasonably suspected neuroendocrine tumour.

Do I need to stop stomach medicines?

Proton pump inhibitors affect the result most, so a doctor usually advises a break of at least two weeks before the blood draw. Do not stop the medicine yourself, particularly if you take it for an ulcer or gastrointestinal bleeding.

Which symptoms may suggest a neuroendocrine tumour?

Many such tumours cause no symptoms for a long time and are found incidentally. Some cause episodes of facial flushing, diarrhoea, wheezing, abdominal pain or weight loss. Many other, more common causes produce the same symptoms, so first show them to a doctor.

How often is chromogranin A checked?

A doctor sets follow-up frequency according to tumour type and treatment, most often alongside regular imaging. For comparison, it is important to use the same laboratory and similar conditions.