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WSVA8-0057
GASTROENTEROLOGY
PARTIAL ANALYTICAL VALIDATION OF A NEW IN- CLINIC CPLI TEST (VCHECK CPL®)
J. Steiner1, J. Liu2, J. Drexel2, C. Chandrashekar2
1Texas A&M University, Gastrointestinal Laboratory, College Station, USA
2Idexx Laboratories, Research and Development, Portland, USA
INTRODUCTION
Serum concentration of pancreatic lipase immunoreactivity (cPLI, measured by Spec cPL®, IDEXX Laboratories) is the most reliable diagnostic tool currently available for the diagnosis of pancreatitis in dogs. A
new in-clinic cPLI test (VCheck cPL®, BioNote), claims similar performance to Spec cPL. However, no analytical validation data are available for this assay.
Your Singapore, the Tropical Garden City
WSVA8-0058
GASTROENTEROLOGY
THE EFFECT OF PANCREATIC LIPASE-RELATED PROTEINS ON SERUM LIPASE ACTIVITY AS MEASURED BY DGGR-BASED ASSAYS
J. Steiner1, P. Guadiano1, R. Gomez1, J. Lidbury1, J. Suchodolski1, F. Carriere2
1Texas A&M University, Gastrointestinal Laboratory, College Station, USA
2CNRS, Bioenergetics and Engineering of Proteins Lab, Marseille, France
INTRODUCTION
Serum lipase activity can be measured using a wide variety of assays that utilize different substrates. In the early nineties a new synthetic substrate, 1,2-O-dilauryl- rac-glycero-3-glutaric acid-(6-methylresorufin) ester (DGGR) was introduced and was initially believed to be specifically hydrolyzed by pancreatic lipase. Previous studies in humans and dogs have shown however
that DGGR-based assays are not specific for the measurement of pancreatic lipase. The exact sources of lipase activity measured by DGGR-based assays in dog sera remain unknown.
OBJECTIVES
To determine the impact of pancreatic lipase-related proteins 1 and 2 (PLRP1 and PLRP2) on serum lipase activity as measured by DGGR-based assays.
METHODS
Serum lipase activity was measured using DGGR-based assays (Diazyme on a Sirrus analyzer and EUROLyser)
in 3 different canine serum samples before and after addition of various concentrations of recombinant human PLRP1 or PLRP2.
RESULTS
Addition of up to 500 mg/L rhPLRP1 or 5 mg/L rhPLRP2 to canine serum samples had no impact on serum lipase activity using either the Diazyme or the EUROLyser assays. However, addition of 50 or 500 mg/L rhPLRP2 led to up to 10-fold increases of serum lipase activity using either assay.
CONCLUSIONS
This study confirms that DGGR is not specifically hydrolyzed by pancreatic lipase. Furthermore, DGGR is a viable substrate for PLRP2. As PLPR2 can be synthesized by extrapancreatic sources this finding could be clinically relevant. Further studies are needed to determine the clinical impact of PLRP2 on serum lipase activity as measured by DGGR-based assays in canine patients.
    OBJECTIVES
To partially analytically validate the VCheck cPL assay.
METHODS
Leftover clinical serum samples were used. VCheck cPL testing (with a V200 analyzer) was performed according to manufacturer’s instructions. Linearity was evaluated by diluting 2 samples 3 times. Precision was evaluated by determining intra-assay variability for two samples analyzed 12 times on the same day. Reproducibility was evaluated by calculating inter-assay variability for 6 samples measured 10 times on different days. Samples (n=42) throughout the working range were assessed for correlation with Spec cPL.
RESULTS
Mean ±SD observed/expected ratio for dilutions were 47.6% ±16.1%. Intra-assay variability for the two samples were 23% and 36%. Inter-assay variability for the 6 samples were 27, 32, 37, 44, 46, and 56%. Furthermore, repeated measurements often changed diagnostic bins for the samples tested. Of 42 clinical samples, 34 (81%) returned lower cPL values by VCheck compared to Spec cPL (Figure 1).
CONCLUSIONS
The new VCheck cPL assay lacked linearity, precision, and reproducibility, suggesting that this assay is not reliable for clinical use. It also frequently provided lower results than Spec cPL, suggesting that reference intervals and cut-off values established for Spec cPL cannot be utilized for the VCheck cPL assay.
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