Chromogranin A
A protein released by neuroendocrine cells throughout the body. It is the main general blood marker for neuroendocrine tumours (such as carcinoid tumours), used to help diagnose them and to follow the disease — but common things like acid-suppressing medicines also raise it.
What it measures
Chromogranin A is a protein stored and released alongside hormones by neuroendocrine cells — a family of hormone-producing cells scattered through the gut, pancreas, lungs and elsewhere. When these cells form a tumour (a neuroendocrine tumour, or NET, of which carcinoid tumours are the best-known example), they often release chromogranin A into the blood in larger amounts, which is why it serves as the main general blood marker for this whole group of tumours. It is used to help support a diagnosis when a NET is suspected, to gauge tumour bulk, and — importantly — to monitor the disease over time, since a rising or falling level can track progression or response to treatment. It is a broad marker: it does not tell you which type of NET is present or where it is, so it is used together with more specific tests such as 5-HIAA (for serotonin-producing carcinoid tumours) and imaging. A major caveat is that chromogranin A is commonly raised by things that have nothing to do with a tumour — above all proton-pump inhibitor acid-suppressing medicines, and also reduced kidney function, chronic gastritis and some other conditions — so a mildly raised level is often a false alarm and must be interpreted with care.
What a high value can mean
- Neuroendocrine tumour (including carcinoid) — the key use; helps diagnose and monitor.
- Proton-pump inhibitor (acid-suppressing) medicines — a very common non-tumour cause of a raised level.
- Reduced kidney function — raises it independently.
- Chronic atrophic gastritis — can elevate it.
- Heart failure and some other chronic conditions — occasional causes.
What a low value can mean
- Normal or low — the expected result; a falling level during NET treatment can indicate a response.
When to discuss with a doctor
Chromogranin A is a specialist marker, used mainly within the diagnosis and long-term monitoring of neuroendocrine tumours rather than as a general screen. Its greatest value is in following a known or suspected NET over time, where the trend matters more than a single figure. Because acid-suppressing medicines and reduced kidney function commonly raise it without any tumour, a mildly high result is frequently a false alarm and needs interpreting against medicines, kidney function and other tests before it means anything. Mediora.AI can surface a raised chromogranin A and track its trend across your results, but confirming or excluding a neuroendocrine tumour is a specialist assessment combining this with more specific markers and imaging — the interpretation belongs with your doctor.