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 (< or =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.
Graca
Roberta
R
Department of Veterinary Pathobiology, University of Illinois-Champagne, Urbana, IL, USA. rgraca@cvm.uiuc.edu
Messick
Joanne
J
McCullough
Sheila
S
Barger
Anne
A
Hoffmann
Walter
W
D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis* / Q000201:enzymology; D004285:Dogs; D005977:Glutarates; D008049:Lipase / Q000378:metabolism*; D010078:Oxazines; D010179:Pancreas / Q000201:enzymology; D010195:Pancreatitis / Q000175:diagnosis / Q000662:veterinary*; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013379:Substrate Specificity
C501502:1,2-o-dilauryl-rac-glycero glutaric acid-(6'-methyl resorufin) ester; D005977:Glutarates; D010078:Oxazines; D008049:Lipase