fPLI is an acronym for feline Pancreatic Lipase Immunoreactivity, a specific lipase found only in feline pancreatic tissue.
The commercially available assay measures concentrations of pancreatic lipase in the serum.
Inflammation of the pancreas leads to an increased release of pancreatic lipase into the circulation, thus elevated concentrations of pancreatic lipase are consistent with a diagnosis of pancreatitis .
Uses
Alone
Feline pancreatic lipase is an enzyme that is synthesized and released only by pancreatic acinar cells.
Increased serum concentrations of feline pancreatic lipase suggest an increased release from pancreatic acinar cells. The increased release of pancreatic lipase is classically associated with pancreatic inflammation, ie acute or chronic pancreatitis.
Clinically normal cats have low circulating concentrations of pancreatic lipase in serum.
Cats with acute pancreatitis typically show dramatic elevations in serum pancreatic lipase concentrations.
In comparison to feline trypsin-like immunoreactivity (fTLI ), pancreatic lipase immunoreactivity concentrations tend to show a greater increase during a bout of acute pancreatitis, and remain elevated for longer periods.
Measurement of an elevated feline pancreatic lipase concentration in serum is a useful method for diagnosing acute or chronic pancreatitis.
The magnitude of elevation of serum feline pancreatic lipase concentration does not establish a prognosis for a patient with acute pancreatitis.
Cats with exocrine pancreatic insufficiency show low to non-detectable concentrations of feline pancreatic lipase in the circulation. Some clinically normal cats, however, also show low concentrations of pancreatic lipase and thus this test can not be used to diagnose exocrine pancreatic insufficiency .
In combination
Many cats with clinical signs of chronic pancreatitis (inappetence, sporadic vomiting, diarrhea, or other) also have concurrent small intestinal disease.
Measurement of feline pancreatic lipase concentration in combination with serum fTLI, cobalamin and folate concentrations may be used to screen patients for small intestinal disease.
Feline pancreatic lipase immunoreactivity is measured in serum.
Quantity of test material
A minimum serum volume of 0.5 ml is recommended, a volume of 1.0 ml serum is preferred.
Sample collection technique
Serum may be harvested from plain clot tubes or serum separator tubes.
Quality control
Precautions
While mild hemolysis and/or lipemia do not interfere with the test methodology, it is best to avoid submission of severely lipemic samples.
Timing of test
Wherever possible, serum should be obtained after a 12 hour fast.
Sample storage
Serum should be harvested from the clotted blood or separator tube before storage.
Feline pancreatic lipase immunoreactivity in serum is stable under refrigeration (4°C) for at least three weeks.
Feline pancreatic lipase immunoreactivity in serum is stable for extended periods (years) if frozen (-20°C or -70°C).
Sample transport
Postal submission of the sample to the laboratory is acceptable . However, as the main use of this test is to aid in the diagnosis of acute pancreatitis, courier submission is recommended to ensure timely receipt of results.
Serum feline pancreatic lipase immunoreactivity is measured with an ELISA .
This test is available exclusively from the Gastrointestinal Laboratory at the Texas A&M University.
A microplate is coated with monoclonal antibodies against feline pancreatic lipase.
Sera are diluted and incubated on the plate, allowing the monoclonal antibodies to capture the pancreatic lipase, while other proteins are washed away.
A secondary antibody carrying a label is then incubated in the wells.
The amount of bound label is proportionate to the quantity of pancreatic lipase in the original serum sample.
A standard curve is constructed using a recombinant peptide that is part of the native canine pancreatic lipase protein.
Availability
Serum feline pancreatic lipase immunoreactivity measurement (fPLI Assay) is currently only available via the Gastrointestinal Laboratory at Texas A&M University.
Validity
Sensitivity
Determination of feline pancreatic lipase in serum has a sensitivity of 82% for the diagnosis of pancreatitis.
Specificity
Determination of feline pancreatic lipase generally has >95% specificity for the diagnosis of pancreatitis. Specificities of 100% have been reported in some studies.
Technique (intrinsic) limitations
Avoid submission of severely lipemic or hemolyzed samples.
The reference range for serum pancreatic lipase immunoreactivity as measured by the fPLI assay in cats is 2.0-6.8 µg/L.
Abnormal values
Cats with serum pancreatic lipase >6.8 but <12 µg/L may have pancreatitis that is mild or resolving. Continue supportive therapy as necessary, consider retesting in 24-48 hours depending on clinical progress.
The cut-off value for diagnosis of pancreatitis is >12 µg/L.
Forman M A, Marks S L, De Cock H E V, Hergesell E J, Wisner E R, Baker T W, Kass P H, Steiner J M & Williams D A (2004) Evaluation of serum feline pancreatic lipase immunoreactivity and helical computed tomography versus conventional testing for the diagnosis of feline pancreatitis. J Vet Intern Med 18 (6), 807-815 PubMed.
Steiner J M, Wilson B G & Williams D A (2004) Development and analytical validation of a radioimmunoassay for the measurement of feline pancreatic lipase immunoreactivity in serum. Can J Vet Res68 (4), 309-314 PubMed.
Steiner J M, Wilson B G & Williams D A (2003) Purification and partial characterization of feline classical pancreatic lipase. Comp Biochem Physiol B Biochem Mol Biol 134 (1), 151-159.
Vetstream contributor(s)
Dr Craig G Ruaux BVSc PhD MACVSc, Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis OR 97331, USA.
Dr Jörg Steiner BVetMed PhD DACVIM DECVIM-CA, Gastrointestinal Laboratory, Department of Small Animal Clinical Sciences, Texas A&M University, 4474 TAMU, College Station, TX 77843-4476, USA.
Organization(s)
The Gastrointestinal Laboratory, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station TX 77845-4474, USA; www.cvm.tamu.edu/gilab.
