Chromogranin A Testing

A test for Chromogranin A (CgA) measures the amount of Chromogranin A in the blood. Chromogranin A is a type of tumour marker.

Chromogranin A may be found in higher-than-normal amounts in patients with certain neuroendocrine tumours (NETs), small cell lung cancer, prostate cancer, and other conditions.  In addition to cancer, elevated CgA levels can occur in:

  • Patients on proton pump inhibitor treatment or other acid suppressive medications (e.g., gastritis). Lack of gastric acids can stimulate the growth of cells to secrete CgA.
  • Renal failure may increase detectable CgA by reducing glomerular filtration of CgA-related peptides.
  • Patients with chronic or acute inflammation and cardiac insufficiency.
  • Patients with untreated hypertension.
  • Patients with non-malignant gastro intestinal disorders (e.g., pancreatitis, chronic hepatitis).
  • Food intake or strenuous exercise before the test.

Your doctor may order a CgA test for one of several reasons:

  • To help diagnose carcinoid tumours and other neuroendocrine tumours.
  • To monitor treatment response. CgA levels may provide information about whether cancer treatment is working.  CgA may also be measured over time to check for changes in levels that could indicate a possible recurrence of the tumour after treatment is completed.
  • To determine prognosis. Testing CgA levels may help doctors understand prognosis, or the chance of recovery.

Click here for more information on the use of Chromogranin A as a tumour marker for prostate cancer.