What it is
Chromogranin A is a protein stored with hormones inside nerve and endocrine cells. UniProt's record (P10645) gives a 457-residue precursor; removing an 18-residue signal sequence leaves 439 amino acids. It is packed into the secretory granules — the small sacs in which cells of the adrenal gland, pituitary, pancreas and gut keep their hormones until release — and is released alongside them.
At 439 residues it is a protein, about eleven times the 40-residue line US regulation uses for proteins (21 CFR 600.3; see peptide versus protein). The library carries it because it is the parent of a whole family of peptides, cut from it inside the granule, and because readers meet it as a tumour-marker result.
The peptides cut from it
UniProt annotates more than a dozen named fragments. The best known:
| Fragment | Precursor residues | Length | What it was found doing |
|---|---|---|---|
| Vasostatin-1 | 19–94 | 76 | — |
| Pancreastatin | 272–319 | 48 | Inhibited insulin release (pig pancreas, 1986) |
| WE-14 | 342–355 | 14 | — |
| Catestatin | 370–390 | 21 | Inhibited catecholamine release (cells, 1997) |
| Serpinin | 429–454 | 26 | Granule formation (UniProt) |
Lengths counted from UniProt's residue ranges for the human protein. Pancreastatin was first sequenced in pig as 49 residues.
Pancreastatin came first. In 1986 Tatemoto and colleagues (Nature, PMID 3537810), searching pig pancreas for peptides ending in an amide group, isolated a 49-residue peptide that "strongly inhibits glucose-induced insulin release from the isolated perfused pancreas". UniProt now annotates it as a fragment of chromogranin A.
Catestatin was found by testing pieces of the parent. In 1997 Mahata and colleagues at UC San Diego (J Clin Invest, PMID 9294131) made 15 synthetic peptides spanning about 80% of (bovine) chromogranin A; one inhibited nicotine-stimulated release of catecholamines — adrenaline and noradrenaline — from cultured adrenal and tumour cells, with half-maximal inhibition at about 200 nM. They proposed it as a local brake on catecholamine release.
Both findings come from animal tissue and cell work. The fragments are research subjects; none is a medicine.
The parent protein's own job
UniProt's annotation for the full protein is that it regulates granule formation in endocrine cells, by raising production of protease nexin 1, which protects granule proteins from being broken down so the granules can form. The fragments' annotations add effects on insulin release, catecholamine release, blood vessels, mast cells and bacteria — each from laboratory studies cited in the record.
The blood test, and why it can mislead
Because many neuroendocrine tumours release chromogranin A, its blood level is used to help follow those tumours. It is not a cancer screening test.
The difficulty is that it rises for other reasons. A 2025 narrative review by authors at Sapienza University of Rome and the University of Bologna (Romano et al., Transl Gastroenterol Hepatol, PMID 40755718) examined the conditions outside tumours that raise it and names chronic atrophic gastritis, proton pump inhibitor use — the common heartburn and ulcer medicines — and inflammatory bowel disease among them, raising levels "often without any malignant association". The authors' conclusion is that a raised level needs cautious interpretation "to avoid misdiagnosis and unnecessary anxiety in patients".
What a reading means for any one person is for the clinician who ordered it. This entry does not interpret results, gives no reference range (laboratories set their own), and a medicine named above is not a reason to stop taking it.
Where it stands
- No medicine is made from chromogranin A or its fragments.
- Its main use is as a blood test in neuroendocrine-tumour care, with known non-tumour causes of a raised value.
- Published record: PubMed returns 7,154 records for chromogranin A, 54 tagged as randomised controlled trials (largely measuring it as an outcome); ClinicalTrials.gov lists 160 studies (all 2026-10-27).
Related reading
DOTATATE and octreotide are the library's entries on the somatostatin-based agents used to image and treat neuroendocrine tumours, and somatostatin is the hormone they copy. The C-peptide cut out when insulin is made is another fragment people meet as a lab result.