Chromogranin A Unit Converter
Chromogranin A Unit Converter
Convert chromogranin A between ng/mL, µg/L and ng/L — and read the interference that dominates the test: proton pump inhibitors raise chromogranin A into the range seen with tumour, and must be stopped before the sample is taken.
Chromogranin A converter
Mass ladder onlyChromogranin A 45.2 ng/mL
The units, and why there is no molar conversion and no band
ng/L = ng/mL × 1000
no nmol/L: chromogranin A is exempt from molar conversion on this site
- ng/mL = µg/L
- a nanogram per millilitre and a microgram per litre are the same concentration, and one or the other is what almost every chromogranin A report prints
- ng/L = ng/mL × 1000
- occasionally seen on European reports. A chromogranin A of 45 ng/mL is 45,000 ng/L, and a thousandfold slip between the two is the only real arithmetic hazard on this page
- why there is no nmol/L
- chromogranin A is a 439-residue acidic secretory protein that is extensively cleaved in the secretory granule into a family of biologically active fragments — vasostatins, pancreastatin, catestatin, WE-14. Different assays are directed at different epitopes and therefore measure different mixtures of intact protein and fragments, so no single molecular weight describes what any of them reports. This site declares no molar unit for chromogranin A for that reason
- why there is no reference interval here
- the cut-off belongs to the assay. Labcorp quotes 0.0–101.8 ng/mL on the Thermo Fisher BRAHMS KRYPTOR assay and the University of Iowa Diagnostic Laboratories quotes 0–103 ng/mL by immunofluorescence, but ELISA and radioimmunoassay methods, and serum against plasma, give materially different numbers. Printing one interval under a converter that anybody’s result can be typed into would be misleading
- so trend on one method
- the manufacturers’ own guidance is that values obtained with different assay methods should not be used interchangeably in serial testing. If chromogranin A is being followed to monitor a neuroendocrine tumour, it must stay on a single assay in a single laboratory for the trend to mean anything
Worked example
Chromogranin A 45.2 ng/mL
45.2 ng/mL = 45.2 µg/L — the same number in the other mass convention
45.2 × 1000 = 45,200 ng/L, the unit some European reports use
There is no nmol/L figure, and that is deliberate: chromogranin A is cleaved into a family of fragments that different assays measure to different extents, so no single molecular weight describes the analyte
This page prints no reference interval either. For scale, Labcorp quotes 0.0–101.8 ng/mL on the BRAHMS KRYPTOR assay and Iowa 0–103 ng/mL by immunofluorescence — but an ELISA result cannot be read against either
And before reading 45.2 as reassuring or 450 as alarming, establish whether the patient was taking a proton pump inhibitor. On a PPI, chromogranin A is commonly many times the upper limit with no tumour present at all
What raises chromogranin A other than a tumour
| Cause | Magnitude | Mechanism |
|---|---|---|
| Proton pump inhibitors | Large — commonly several times, sometimes more than ten times the upper limit | Acid suppression removes the negative feedback on antral gastrin; the resulting hypergastrinaemia drives gastric enterochromaffin-like cell hyperplasia, and those cells secrete chromogranin A. Stop the PPI for at least two weeks before testing |
| Atrophic gastritis, and any other cause of achlorhydria | Often marked | The same mechanism as PPIs, arrived at by a different route — no acid, high gastrin, ECL-cell hyperplasia |
| Renal impairment | Proportionate to the fall in function | Reduced clearance; chromogranin A rises as eGFR falls |
| Heart failure | Mild to moderate | Raised in chronic heart failure and related to its severity |
| Histamine H2-receptor antagonists | Little or none | Weaker acid suppression than a PPI, so far less gastrin drive — a useful substitute while a PPI is withheld |
| Neuroendocrine tumour | Variable; broadly reflects tumour burden | The intended finding, and the reason the list above matters so much |
Two named intervals, two methods, and why they are not interchangeable
| Laboratory | Method | Quoted interval |
|---|---|---|
| Labcorp (test 140848) | Thermo Fisher BRAHMS KRYPTOR, time-resolved amplified cryptate emission | 0.0–101.8 ng/mL |
| University of Iowa Diagnostic Laboratories | Immunofluorescence | 0–103 ng/mL |
| Other platforms — ELISA, radioimmunoassay, serum against plasma | Different epitopes, different calibrants, different fragment recognition | Materially different numbers; no single conversion between them |
A general marker with a specific problem
Chromogranin A is an acidic protein stored in the secretory granules of neuroendocrine cells and released with their hormones. That makes it a general neuroendocrine tumour marker rather than a specific one: it is raised across gastroenteropancreatic neuroendocrine tumours, phaeochromocytoma and small-cell lung cancer, it broadly reflects tumour burden, and its main practical use is monitoring — watching a treated tumour for progression or response — rather than diagnosis. Alongside urinary 5-HIAA it is one of the two first-line biochemical tests when carcinoid syndrome is suspected.
The interference that dominates the test is pharmacological. Proton pump inhibitors raise chromogranin A substantially, commonly several times and sometimes more than ten times the upper limit of normal — well into the range a neuroendocrine tumour would produce. The mechanism is worth knowing because it explains the company this analyte keeps: suppressing gastric acid removes the feedback inhibition on antral G cells, gastrin rises, and sustained hypergastrinaemia drives hyperplasia of gastric enterochromaffin-like cells, which secrete chromogranin A. Exactly the same chain raises both chromogranin A and gastrin, which is why the two are so often misread together, and exactly the same chain operates in atrophic gastritis and in any other cause of achlorhydria without a drug being involved. The practical consequence is that a proton pump inhibitor must be stopped before the sample is taken — the University of Iowa Diagnostic Laboratories instructs at least two weeks — and that an H2-receptor antagonist, whose acid suppression is weaker, is the usual cover in the interim. Renal impairment, heart failure and untreated hypertension also raise chromogranin A, so renal function belongs beside any elevated result.
This page prints no reference interval, and that is the same decision the troponin I converter makes for the same reason: the cut-off belongs to the assay, not to the analyte. Labcorp quotes 0.0 to 101.8 ng/mL on the BRAHMS KRYPTOR platform and the University of Iowa quotes 0 to 103 ng/mL by immunofluorescence, but ELISA and radioimmunoassay methods, and serum against plasma, give materially different figures, because chromogranin A circulates as a mixture of the intact 439-residue protein and the fragments cleaved from it — vasostatins, pancreastatin, catestatin — and each assay recognises a different part of that mixture. Labcorp’s own guidance is that values from different methods should not be used interchangeably in serial testing. So trend the number on one assay in one laboratory, treat a change of platform as a new baseline, and read the interval printed beside your own result rather than any interval printed here.
For the same reason there is no molar conversion. No single molecular weight describes a protein that is measured as a variable mixture of itself and its cleavage products, so this site declares chromogranin A exempt from molar conversion rather than offering a nmol/L figure that would look precise and mean nothing. What is left is a mass ladder: nanograms per millilitre and micrograms per litre are the same number, and nanograms per litre is that number multiplied by a thousand.
Frequently asked questions
Do proton pump inhibitors affect chromogranin A?
Substantially — commonly several times and sometimes more than ten times the upper limit of normal, which is the range a neuroendocrine tumour produces. Acid suppression raises gastrin, and sustained hypergastrinaemia causes gastric enterochromaffin-like cell hyperplasia, which secretes chromogranin A. The University of Iowa Diagnostic Laboratories instructs that PPI treatment be stopped for at least two weeks before testing.
What is a normal chromogranin A level?
It depends entirely on the assay, which is why this page prints no interval. Labcorp quotes 0.0–101.8 ng/mL on the BRAHMS KRYPTOR method and the University of Iowa 0–103 ng/mL by immunofluorescence, but ELISA and radioimmunoassay figures differ materially and are not interchangeable. Use the interval printed beside your own result.
How do I convert chromogranin A from ng/mL to µg/L?
You do not need to — they are the same number. A chromogranin A of 45.2 ng/mL is 45.2 µg/L. The only conversion on this page with any arithmetic in it is ng/L, which is the same value multiplied by a thousand: 45.2 ng/mL is 45,200 ng/L.
Why is there no nmol/L conversion for chromogranin A?
Because the analyte is not one molecule. Chromogranin A is cleaved in the secretory granule into a family of fragments — vasostatins, pancreastatin, catestatin — and different assays measure different mixtures of intact protein and fragments. No single molecular weight describes what is being reported, so no molar figure is offered.
What else raises chromogranin A besides a tumour?
Atrophic gastritis and any other cause of achlorhydria, by the same gastrin-driven mechanism as proton pump inhibitors; renal impairment, through reduced clearance; and heart failure. H2-receptor antagonists have much less effect than PPIs, which makes them the usual cover while a PPI is withheld before testing.
Related calculators
References
- Labcorp. Test 140848: Chromogranin A — reference interval 0.0–101.8 ng/mL, Thermo Fisher BRAHMS KRYPTOR (TRACE) assay; chronic proton pump inhibitor use can produce elevations many times above the normal range; values obtained with different assay methods should not be used interchangeably. Accessed 2026.
- University of Iowa Diagnostic Laboratories. Chromogranin A — reference range 0–103 ng/mL by immunofluorescence; stop proton pump inhibitor treatment for at least two weeks prior to testing. Accessed 2026.
- Sanduleanu S, De Bruïne A, Stridsberg M, et al. Serum chromogranin A as a screening test for gastric enterochromaffin-like cell hyperplasia during acid-suppressive therapy. Eur J Clin Invest. 2001;31(9):802–811.
- O’Toole D, Grossman A, Gross D, et al. ENETS consensus guidelines for the standards of care in neuroendocrine tumors: biochemical markers. Neuroendocrinology. 2009;90(2):194–202.
Medical Disclaimer: The tools and content provided here are for educational and reference purposes only. They are not intended to substitute for professional medical advice, diagnosis, or treatment. Clinical decisions should always be based on the comprehensive assessment of a qualified healthcare professional.