Chromogranin - A

Raised chromogranin A (CgA) suggests increased neuroendocrine cell activity—often seen with neuroendocrine tumors—but is not specific. Levels can also rise with proton pump inhibitors, kidney impairment, chronic atrophic gastritis, liver disease, and some inflammatory conditions. A high result prompts clinical correlation, repeat testing (after stopping PPIs when possible), and further imaging or biopsy to identify or exclude a neuroendocrine tumor.

Chromogranin A (CgA) is a blood biomarker produced by neuroendocrine cells and used to detect and monitor neuroendocrine tumors (e.g., carcinoid, pancreatic NETs, pheochromocytoma). Elevated CgA suggests tumor activity but is nonspecific: levels rise with proton‑pump inhibitor use, renal failure, chronic atrophic gastritis and other conditions. It’s most useful alongside imaging and clinical assessment; stop PPIs before testing when possible.

Chromogranin is positive in tumors with neuroendocrine differentiation, including carcinoid (bronchial and gastrointestinal) and pancreatic neuroendocrine tumors (insulinoma, gastrinoma), small‑cell lung carcinoma, medullary thyroid carcinoma, pheochromocytoma and paraganglioma, neuroblastoma, Merkel cell carcinoma, and many pituitary and parathyroid neoplasms. Chromogranin A/B are commonly used immunohistochemical markers to detect and classify neuroendocrine tumors and metastases.

Chromogranin A (CgA) reference ranges vary by laboratory and assay, but typical upper limits for plasma/serum are about 80–100 ng/mL (often quoted as <100 ng/mL). Some labs report normal ranges from ~25–150 ng/mL. Values can be falsely elevated by proton‑pump inhibitors, renal impairment, and other conditions, so interpret results using the specific lab’s reference interval.

Proton pump inhibitors (omeprazole, esomeprazole, pantoprazole, lansoprazole) are the most common medications that raise chromogranin A. H2‑receptor antagonists (ranitidine, famotidine) can also modestly increase levels. These acid‑suppressing drugs elevate CgA by causing hypergastrinemia and enterochromaffin‑like cell stimulation; clinicians often advise stopping PPIs (and withholding H2 blockers when safe) before testing.

High-grade neuroendocrine tumors are managed by a multidisciplinary team. Systemic platinum‑based chemotherapy (cisplatin or carboplatin with etoposide) is first‑line for most high‑grade cases; surgery is considered for localized disease. Radiotherapy, liver‑directed treatments, and supportive care help control symptoms. Somatostatin analogues are generally less effective; selected patients may be eligible for targeted therapies, peptide receptor radionuclide therapy, or clinical trials.