Chromogranin A (CgA) analysis is the most accurate test for detecting neuroendocrine tumors

Has your doctor asked you to take a Chromogranin A (CgA) test?
This might be the first time you’ve heard of this type of test, as it’s not part of routine blood work. Instead, it’s a specialized test used to detect certain types of tumors.In this article from Dalili Medical, we provide you with a comprehensive guide to understanding the CgA test:
What is it? When is it requested? What do the results mean? And why is it considered an important marker in diagnosing neuroendocrine tumors?

✅ What is the Chromogranin A (CgA) Test?

The Chromogranin A (CgA) test is a blood test used to measure the level of a protein secreted by neuroendocrine cells—specialized cells found in the nervous system and endocrine glands that produce hormones.

An elevated CgA level in the blood may indicate the presence of a neuroendocrine tumor (NET)—a rare type of tumor that most commonly arises in the digestive tract, pancreas, or lungs.

 Why Is the CgA Test Ordered?

Your doctor may order a Chromogranin A test in the following cases:

• When a neuroendocrine tumor (NET) is suspected.

• To monitor an already diagnosed NET patient.

• To evaluate treatment effectiveness, such as after surgery or chemotherapy.

• As part of post-treatment follow-up to detect any recurrence of the tumor.

⚙️ How Is the Chromogranin A Test Performed?

• A simple venous blood sample is drawn.

• Fasting is not always required, but the test is usually done in the morning.

• It is recommended to stop taking certain medications (like acid reducers) before the test, based on your doctor’s advice.

• The sample is sent to a lab, and results are typically available within 1–2 days.

 Do Any Medications Affect the Test Results?

Yes. It’s important to inform your doctor about any medications you're taking, especially:

• Proton pump inhibitors (PPIs) such as omeprazole or esomeprazole, which may increase CgA levels and lead to false-positive results.

• Certain heart medications.

• Severe liver or inflammatory conditions.

 It's often advised to discontinue PPIs for at least two weeks before the test, if possible.

 Interpreting CgA Test Results

✅ Normal Result:

• Values vary slightly between labs, but are usually below 100 ng/mL.

❗ Elevated CgA Levels:

May indicate:

• Presence of a neuroendocrine tumor (NET), such as:

  • Carcinoid tumor

  • Gastrinoma, insulinoma, or glucagonoma

  • NETs in the pancreas, stomach, or lungs

• Chronic kidney disease

• Severe liver disease or inflammation

• Long-term use of acid-suppressing medications (PPIs)

⚠️ Low CgA Levels:

Generally not clinically significant, but may suggest a positive response to treatment or tumor regression.

 What Are Neuroendocrine Tumors (NETs)?

NETs are rare tumors that arise from cells with both nervous and hormonal functions.
They usually grow slowly, but can produce hormones that lead to troubling symptoms like:

• Chronic diarrhea

• Facial flushing

• Blood sugar imbalances

They range from benign to malignant, and CgA testing is one of the most important markers for detecting and monitoring these tumors.

❓ Frequently Asked Questions About the CgA Test

Does a high CgA level always mean cancer?

❌ Not necessarily. Other causes include:

• Use of proton pump inhibitors (PPIs)

• Liver or kidney disease

• Severe inflammatory conditions

Can the CgA test be used alone for diagnosis?

❌ No. It serves as an initial indicator, but should be followed by:

• Imaging tests (CT, MRI, PET scans)

• Biopsies

• Other hormone-related tests

Is it useful for monitoring treatment?

✅ Yes. The test is highly useful for tracking tumor progression, treatment response, and detecting recurrence.

Can children take the CgA test?

It’s rarely used in children because NETs are very uncommon in childhood, but it may be performed if medically necessary.

 Medical Advice:

If your CgA test shows elevated levels, don’t panic. A high result doesn’t automatically mean you have a tumor.
You should always consult a specialist in neuroendocrine or gastrointestinal tumors, and follow up with additional diagnostic tests.

✍️ Summary

The Chromogranin A (CgA) test is a valuable tool for detecting and monitoring neuroendocrine tumors (NETs).
Though not a routine test, it offers essential insight in specific medical situations—especially if there are concerning symptoms or a prior diagnosis.If your doctor recommends this test, be sure to follow preparation instructions carefully, and review the results with a qualified specialist.