Examinations
Examinations
This test measures the amount of chromogranin A (CgA) in the blood. CgA is a protein found in and secreted by neuroendocrine cells.
Both benign and malignant tumors can arise from neuroendocrine cells and endocrine (hormonal) system glands. These tumors include:
- Carcinoid tumors
- Insulinomas
- Small cell lung cancer (SCLC)
- Neuroblastomas
- Other neuroendocrine tumors
Many of these tumors secrete large amounts of hormones (e.g., serotonin, catecholamines, insulin), leading to characteristic symptoms that may be persistent or intermittent. However, some neuroendocrine tumors do not secrete expected hormones.
Regardless of hormone secretion, neuroendocrine tumors are often associated with elevated CgA levels.
- Sample: Blood drawn from a vein.
- Fasting for at least 12 hours before the test is required.
- Discontinue medications 24 hours before testing (if approved by the doctor).
- Diagnosis, monitoring, and prognosis of neuroendocrine tumors
- Patients with symptoms suggestive of neuroendocrine tumors, such as:
- Flushing (redness of the face and neck)
- Increased heart rate (tachycardia)
- High blood pressure and chest pain
- Abdominal pain, nausea, vomiting, diarrhea
- Asthma-like attacks (bronchospasm)
Clinical Use
- CgA levels are measured not only for initial diagnosis but also to assess treatment effectiveness and monitor tumor recurrence.
Factors That May Increase Chromogranin A Levels (Non-Tumor Causes)
- Chronic atrophic gastritis (Type A gastritis)
- Long-term use of proton pump inhibitors (PPIs) (e.g., omeprazole, pantoprazole, lansoprazole, rabeprazole) or
H2 receptor blockers (e.g., ranitidine, famotidine, nizatidine, roxatidine) - Kidney dysfunction
- Hypertension (high blood pressure)
- Heart disease
- Rheumatoid arthritis
- Inflammatory bowel disease (IBD)
Important Considerations
Although CgA levels can increase in the above conditions, they are significantly lower compared to levels observed in neuroendocrine tumors.