The Assay
The CE/IVD marked suPARnostic® ELISA assay is a simplified double monoclonal antibody sandwich assay whereby samples and peroxidase-conjugated anti-suPAR are first mixed together and then incubated in anti-suPAR pre-coated micro wells. The recombinant suPAR standards of the kit are calibrated against healthy human blood donor sam¬ples. suPAR concentrations determined with the kit are given as ng/mL plasma.
In the assay, suPAR standards, blank, curve control and patient samples are mixed in white micro wells together with peroxidase-conjugated anti-suPAR. After mixing, the solutions of sample and conjugate are transferred with a multi-channel pipette from white to clear micro wells, in the plates provided, which are pre-coated with anti-suPAR, in duplicates.
During a one hour incubation period in the dark, a sandwich is formed consisting of solid-phase antibody, suPAR and the peroxidase-conjugated antibody.
Following a washing step, during which unbound material is removed, a chromogenic substrate is added to the wells. The more suPAR a sample contains, the more intense is the blue color which is developed.
After an additional 20 minutes incubation in the dark, the color development is stopped by the addition of sulphuric acid which turns the color in the wells to yellow.
The absorbance is measured using a microtiter plate reader, at 450 nm using a 650 nm reference filter. A calibration curve is prepared from the seven suPAR standards and the concentration of suPAR in the patient sample is determined by interpola¬tion.
Safety
Users of the product are not put through any hazard but users should follow reagent precautions and recommendation found in the kit insert page 8.
You can download the kit insert here: 
Elisa Kit insert v. 3 (778.08 KB) .
There are no safety issues concerning the consumption since the test consists of a blood sample taken from the test person.
Product Stability
Preliminary stability data indicate that the shelf life for the product is 1 year when stored at 4-8°C. Plasma samples taken from patients can be stored at -20°C and -80°C until needed. Another advantage of using the suPARnostic® ELISA kit is, that it is not nessecary to work in a sterile environment.
suPAR Stability
suPAR’s high stability and uniform kinetics make it a reliable clinical biomarker.
Kofoed and co-workers examined suPAR in a stability test and found that suPAR showed very high stability compared to other sepsis markers [Kofoed et al., 2006], confirming results obtained from earlier studies [Riisbro et al., 2001].
The stability test showed that suPAR is the biomarker with the highest stability at room temperature compared to sTREM-1and MIF [Kofoed et al., 2006]. Furthermore, Kofoed and co-workers demonstrated that suPAR remains stable through several freezing/thawing cycles.
This makes suPAR an obvious and reliable biomarker [Kofoed et al., 2006].
These advantages makes the use of suPARnostic® ELISA kit easy to handle, as you can leave your plasma sample on the bench for several hours.
References
suPARnostic Kit insert, (2012) 3rd Edition, 1-23
Kofoed K, Schneider UV, Scheel T, Andersen O, and Eugen-Olsen J, (2006) Clinical Chemistry, 52, 1284-93
Riisbro R, Christensen IJ, Hogdall C, Brunner N, Hogdall E (2001) Int J Biol Markers, 16, 233-9
