suPAR Unit Converter
suPAR Unit Converter
ng/mL and µg/L are the same number for suPAR. There is no molar conversion, because the assay counts full-length suPAR and two cleaved fragments together and reports one figure.
suPAR converter
ng/mL = µg/LsuPAR 5.2 ng/mL
Units, and the molar conversion this page does not offer
pg/mL = ng/mL × 1,000
- ng/mL and µg/L
- the same number. A nanogram per millilitre is a microgram per litre, the thousandfold step down in mass being cancelled by the thousandfold step up in volume. Both appear in the suPAR literature
- pg/mL
- the ng/mL figure × 1,000, used by some research assays. A suPAR of 5.2 ng/mL is 5,200 pg/mL, and the two are easy to confuse because both are plausible-looking numbers
- no nmol/L
- deliberate, and for a different reason from the other mass-only pages on this site. suPAR is not one molecule. The receptor is released from the cell surface when its GPI anchor is cleaved, and is also cut in the linker between its first and second domains, so plasma contains full-length suPAR, the cleaved two-domain fragment and free domain 1 — three species of materially different mass
- what the assay reports
- one number for all three. A single grams-per-mole for “suPAR” would be a weighted average of a mixture whose composition varies between patients, on top of the five N-glycosylation sites of variable occupancy UniProt Q03405 annotates on the receptor
Worked example
suPAR 5.2 ng/mL
5.2 ng/mL = 5.2 µg/L — identical numbers, no arithmetic
5.2 × 1,000 = 5,200 pg/mL
Back again: 5,200 ÷ 1,000 = 5.2 ng/mL, the round trip the grid above performs
The published risk bands of 4 and 6 ng/mL are 4,000 and 6,000 pg/mL
So 5.2 ng/mL sits in the medium-risk band: above the 4 ng/mL low-risk ceiling and below the 6 ng/mL high-risk floor
A research report of 5,200 pg/mL is the same result, and a reader who read it as 5,200 ng/mL would be out by a factor of a thousand
Published suPAR bands, in both units
| Band | ng/mL (µg/L) | pg/mL | Population and source |
|---|---|---|---|
| Low risk | under 4 | under 4,000 | acute medical admissions, emergency department (Seppälä 2021) |
| Medium risk | 4 to 6 | 4,000 to 6,000 | same cohort, same source |
| High risk | above 6 | above 6,000 | same cohort, same source |
| Healthy individuals | under 4 | under 4,000 | ViroGates suPARnostic product information |
| Unselected emergency department patients | about 4 to 6 | about 4,000 to 6,000 | ViroGates suPARnostic product information |
| Critically ill patients | above 6 | above 6,000 | ViroGates suPARnostic product information |
Why one number cannot carry a molar mass
| Circulating species | Where it comes from | Mass |
|---|---|---|
| Full-length suPAR, domains D1 to D3 | GPI anchor cleaved at Gly305 | about 30 kDa of backbone, materially more when glycosylated |
| Cleaved suPAR, domains D2 to D3 | additional cut in the D1–D2 linker | smaller again, and variable with the cleavage site |
| Free domain D1 | the other product of the same cut | smaller still |
A receptor fragment that measures how activated the immune system is
The urokinase plasminogen activator receptor sits on monocytes, neutrophils, activated T cells, endothelium and macrophages, tethered by a glycosylphosphatidylinositol anchor, where it localises urokinase activity and binds vitronectin to drive cell adhesion and migration. When those cells are activated the anchor is cleaved and the receptor is released into plasma as soluble uPAR. The concentration therefore tracks the total burden of immune activation across the body, a genuinely different quantity from anything procalcitonin or C-reactive protein reports.
That generality is both the point and the limitation. suPAR is strongly prognostic and almost entirely non-diagnostic. In an unselected acute medical population it stratifies risk of death and readmission cleanly — below 4 ng/mL low, 4 to 6 medium, above 6 high — and the manufacturer’s figures for healthy people, emergency department attenders and the critically ill fall on the same two boundaries. What it will not tell you is what is wrong: it is raised by age, smoking, obesity, HIV, cardiovascular disease, cancer and above all chronic kidney disease, where it is both a marker and, on current evidence, a candidate contributor to glomerular injury.
It also moves slowly. Where presepsin rises within two hours of a bacterial stimulus and procalcitonin within six, suPAR reflects a chronic state and changes over days — useful for deciding how worried to be about a patient, useless for tracking the response to a dose of antibiotic.
The units are mercifully simple: ng/mL and µg/L are the same number, and pg/mL is a thousand times either, which is the only place to go wrong. There is no nmol/L column, and the reason is specific rather than cautious. suPAR is not a single molecule — the receptor is cut in the linker between its first and second domains as well as at its anchor, so plasma carries full-length suPAR, a two-domain fragment and free domain 1, and the assay counts all three as one number. There is no grams-per-mole for a mixture whose proportions differ between patients, so the table above sets out the three species rather than averaging them into a figure that would look exact. Intervals and thresholds are method- and laboratory-dependent, and your own report’s interval, for the assay that produced the result, takes precedence. This supports a clinician’s judgement rather than replacing it: it is arithmetic on the figures entered, and knows nothing about the patient.
Frequently asked questions
Is ng/mL the same as µg/L for suPAR?
Yes — numerically identical, so 5.2 ng/mL and 5.2 µg/L are the same result. pg/mL is a thousand times that figure, so the same value is 5,200 pg/mL, and that factor of a thousand is the only real trap in suPAR units.
What is a normal suPAR level?
Healthy individuals generally sit below 4 ng/mL. In acute medical admissions a published stratification puts below 4 ng/mL at low risk, 4 to 6 at medium and above 6 at high, with risk meaning all-cause mortality and readmission rather than any particular diagnosis. Both the cohort study and the manufacturer give the same two boundaries.
Why is there no nmol/L conversion for suPAR?
Because suPAR is not one molecule. The receptor is released when its GPI anchor is cleaved and is also cut in the linker between domains 1 and 2, so plasma contains full-length suPAR, a two-domain fragment and free domain 1. The assay measures all three as a single mass concentration, and a molar mass for a patient-dependent mixture would be arithmetic without meaning.
Does suPAR tell me whether a patient has an infection?
No. It measures the degree of immune activation, not its cause, and is raised by age, smoking, obesity, HIV, cardiovascular disease, cancer and chronic kidney disease as well as infection — prognostic rather than diagnostic.
How fast does suPAR change?
Slowly — over days. It reflects a chronic state of immune activation rather than an acute event, which makes it unsuitable for following a response to treatment. Presepsin rises within about two hours of a bacterial stimulus and procalcitonin within three to six.
Related calculators
References
- Seppälä S, Andersen AP, Nyyssönen K, Eugen-Olsen J, Hyppölä H. suPAR cut-offs for stratification of low, medium, and high-risk acute medical patients in the emergency department. BMC Emerg Med. 2021;21(1). doi:10.1186/s12873-021-00544-x
- ViroGates. What is suPAR? suPARnostic product information. (Healthy individuals below 4 ng/mL; unselected emergency department patients about 4–6 ng/mL; critically ill patients above 6 ng/mL.)
- UniProt Knowledgebase entry Q03405 (PLAUR, human): 335 residues, 36,978 Da precursor, mature chain 23–305, GPI anchor Gly305, five N-glycosylation sites, domains D1 23–114, D2 115–213, D3 214–305.
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/