ProGRP Unit Converter
ProGRP Unit Converter
pg/mL and ng/L are the same number for ProGRP. The small-cell lung cancer marker that haemolysis does not touch — but which renal impairment raises markedly, so the kidney function has to be read alongside it.
ProGRP converter
Mass ladder onlyProGRP 38 pg/mL
Formula and conversion factors
ng/mL = pg/mL ÷ 1000
- pg/mL = ng/L
- a picogram per millilitre and a nanogram per litre are the same concentration, so no arithmetic is involved between them
- no molar unit
- the assay measures a stable fragment of the pro-gastrin-releasing peptide precursor against its own calibrator rather than weighing a defined molecule, so no molar conversion applies
- renal function
- ProGRP is cleared by the kidney and is markedly raised in renal impairment; the manufacturer advises checking creatinine when a high result does not fit the clinical picture
- assay dependence
- cut-offs are platform-specific, so a patient must be followed on a single assay for a trend to be meaningful
Worked example
ProGRP 38 pg/mL
38 pg/mL = 38 ng/L — the two units are identical
38 ÷ 1000 = 0.038 ng/mL
No band is shown: the cut-off printed on your own report is the one that applies
If kidney function is impaired, a raised ProGRP must be read against the creatinine before anything else
The three units
| Unit | Relationship | Example |
|---|---|---|
| pg/mL | The usual reporting convention | 38 |
| ng/L | Identical to pg/mL | 38 |
| ng/mL | pg/mL ÷ 1000 | 0.038 |
ProGRP next to NSE
| ProGRP | NSE | |
|---|---|---|
| Main use | Small-cell lung cancer: diagnosis support, prognosis, monitoring | Small-cell lung cancer and neuroblastoma; also prognosis after cardiac arrest |
| Specificity for small-cell histology | Higher — the more discriminating of the two | Lower; raised in a wider range of conditions |
| Affected by haemolysis? | No. The manufacturer cites the absence of false positives from haemolysis as an advantage | Yes, severely. A haemolysed sample is uninterpretable |
| Affected by renal impairment? | Yes, markedly. Renal failure is the main non-malignant cause of a high result | Less so |
| Reported unit | pg/mL, identical to ng/L | ng/mL, identical to µg/L |
| Named assay figure | The Elecsys ProGRP method sheet cites 80.1 pg/mL as discriminating small-cell from non-small-cell lung cancer at 95% specificity | Mayo Clinic Laboratories quote ≤15 ng/mL on the BRAHMS Kryptor assay |
The marker that survives a haemolysed tube
ProGRP is reported in pg/mL or in the identical ng/L, and ng/mL is simply the same number divided by a thousand, so the conversion here needs no thought. The assay measures a stable fragment of pro-gastrin-releasing peptide, the precursor of a hormone secreted by neuroendocrine cells, because the mature peptide itself has a half-life of only minutes and cannot be measured reliably. The fragment is quantified against the assay’s own calibrator, so there is no molar unit.
Its role is in small-cell lung cancer, where it is the more specific of the two conventional markers. The Elecsys method sheet gives 80.1 pg/mL as the concentration that separates small-cell from non-small-cell lung cancer at 95 per cent specificity, with sensitivity around 78 per cent — figures that belong to that platform and are quoted here as an illustration, not as a threshold to apply to a report from elsewhere. In practice ProGRP supports the distinction of small-cell histology, carries prognostic weight, and is used to follow response and detect relapse alongside imaging.
The reason it is measured beside NSE rather than instead of it is that the two fail in different ways. NSE is destroyed by haemolysis, because red cells contain enolase; ProGRP is not, and the manufacturer names the absence of haemolysis-driven false positives as an advantage of the assay. Against that, ProGRP is cleared renally and is markedly raised in renal impairment. A high ProGRP in someone with poor kidney function may be telling you about the kidneys rather than the lungs, and the method sheet itself advises checking the creatinine when a high result does not fit the clinical picture.
This page prints no reference band, because the published cut-offs are manufacturer figures for individual analysers and are not interchangeable. Use the interval on your own report, and keep every sample in a monitoring series on the same assay, since a change of laboratory can create an apparent trend that reflects only the platform. A tumour marker is one input to an assessment made by a clinician who has the imaging and the kidney function; it is not diagnostic on its own.
Frequently asked questions
Is pg/mL the same as ng/L for ProGRP?
Yes, exactly the same number — a picogram per millilitre is a nanogram per litre. ng/mL is that number divided by a thousand, so 38 pg/mL is 38 ng/L and 0.038 ng/mL. There is no molar unit for ProGRP.
Why is ProGRP measured rather than gastrin-releasing peptide itself?
Because the mature peptide has a half-life of only a few minutes in plasma and cannot be measured reliably. The assay targets a stable fragment of its precursor instead, which is present in proportion to secretion but survives long enough to be quantified.
Does haemolysis affect ProGRP?
No, and that is precisely why it is used alongside NSE. Haemolysis releases enolase from red cells and makes an NSE result uninterpretable, but it does not produce false positive ProGRP results. A haemolysed sample can still yield a usable ProGRP.
Can kidney disease raise ProGRP?
Yes, markedly. ProGRP is cleared renally and renal failure is the main non-malignant cause of a high level, so a raised result in someone with impaired kidney function needs that context. The assay manufacturer advises checking serum creatinine when a high ProGRP does not fit the clinical picture.
What is a normal ProGRP?
There is no universal figure. The Elecsys method sheet cites 80.1 pg/mL as the level distinguishing small-cell from non-small-cell lung cancer at 95 per cent specificity on that platform, but cut-offs differ between assays. The interval on your own report is the one that applies, and a clinician should interpret it.
Related calculators
References
- Roche Diagnostics. Elecsys ProGRP method sheet: cut-off 80.1 pg/mL at 95% specificity versus a non-small-cell lung cancer cohort; increased concentrations observed in renal dysfunction; no false positives from haemolysis.
- Molina R, Auge JM, Filella X, et al. Pro-gastrin-releasing peptide (proGRP) in patients with benign and malignant diseases: comparison with CEA, SCC, CYFRA 21-1 and NSE in patients with lung cancer. Anticancer Res. 2005;25(3A):1773–1778.
- Korse CM, Holdenrieder S, Zhi XY, et al. Multicenter evaluation of a new progastrin-releasing peptide (ProGRP) immunoassay across Europe and China. Clin Chim Acta. 2015;438:388–395.
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.