Validation and diagnostic efficacy of a lipase assay using the substrate 1,2-o-dilauryl-rac-glycero glutaric acid-(6′methyl resorufin)-ester for the diagnosis of acute pancreatitis in dogs

Background: Increased serum lipase activity has been used historically to support the diagnosis of acute pancreatitis, a common disease in dogs. Most of the lipase assays that are currently in use lack optimum sensitivity and specificity. Objective: The objectives of this study were to 1) validate the 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6′-methylresorufin) ester (DGGR) assay for determination of lipase activity in canine serum and 2) compare results, reference intervals, sensitivity, and specificity of the DGGR assay with a standard 1,2-diglyceride (1,2 DiG) assay for diagnosing acute pancreatitis in dogs. Methods: Precision, linearity, and interference studies were performed for method validation on a Hitachi 911 analyzer. Lipase results from the DGGR and 1,2 DiG assays were compared by linear regression analysis. Sensitivity, specificity, and diagnostic efficacy were determined for both assays on a population of 30 dogs, 15 of which had acute pancreatitis based on history, clinical signs, and ultrasound findings. Results: Within-run and within-day coefficients of variation (CVs) were low (<3%), with higher day-to-day CVs (≤14 %). The assay was linear between 8 and 2792 U/L. No significant interference by hemolysis and lipemia was found. Poor correlation was found between the assays (r_s = 0.84). The lipase reference interval was 8-120 U/L for the DGGR assay and 30-699 U/L for the 1,2 DiG assay. Sensitivity and specificity for the diagnosis of pancreatitis were 93% and 53%, respectively, for the DGGR assay and 60% and 73% for the 1,2 DiG assay. Receiver operating characteristic curve analysis showed similar areas under the curve. Conclusions: On the basis of this study, the DGGR method is considered adequate for assaying serum lipase activity in dogs. The high sensitivity of the DGGR assay suggests it may be a useful screening test for canine pancreatitis.