chromogranin A
Pronunciation: KROH-moh-gran-in A
A biomarker protein used to diagnose and monitor neuroendocrine tumors of the gastrointestinal tract.
Full Definition
Chromogranin A (CgA) is a glycoprotein found in secretory vesicles of neuroendocrine cells and serves as a crucial biomarker for gastroenteropancreatic neuroendocrine tumors. Elevated serum levels indicate the presence of neuroendocrine malignancy and can be used for initial diagnosis, monitoring treatment response, and detecting recurrence. CgA levels correlate with tumor burden and secretory activity, though levels can be affected by proton pump inhibitor use and renal dysfunction. It is particularly valuable in diagnosing functioning and non-functioning pancreatic neuroendocrine tumors and carcinoid tumors of the small bowel.
Usage
Usage note: Abbreviate as CgA with capital C and lowercase g. Include units (ng/mL) when citing values.
In Context
- "Elevated chromogranin A levels of 850 ng/mL supported the diagnosis of pancreatic neuroendocrine tumor." — Laboratory report
- "Serial chromogranin A measurements showed progressive decline following octreotide therapy." — Clinical progress note