Accuracy of acute‐phase proteins in identifying lethargic and anorectic cats with increased serum feline pancreatic lipase immunoreactivity

Abstract

The mainstay of laboratory diagnostics of feline pancreatitis (FP) is measuring serum feline pancreatic lipase immunoreactivity (fPLI). Thus far, several studies have investigated the relationship between acute‐phase proteins (APPs) and the presence and severity of FP. Although changes in serum amyloid A (SAA) concentration have been linked with FP, its diagnostic accuracy remains unknown. We aimed to determine the accuracy of selected APPs in identifying cats with a high risk of FP based on increased fPLI. Serum fPLI was measured in cats (n = 52) that were presented to veterinary clinics with signs of lethargy and anorexia. The cats were divided into two groups (fPLI ≤3.5 μg/L; n = 27 and fPLI >3.5 μg/L, n = 25), corresponding to low and high risks of FP. Serum albumin, globulin, haptoglobin (Hp), and SAA concentrations, as well as the albumin‐to‐globulin ratio (A/G) and SAA‐to‐albumin (SAA/A) ratios, were determined and compared between groups. The accuracy of these measurements was examined using a multivariable logistic regression model and receiver operator characteristic (ROC) curve analysis. SAA concentrations and SAA/A ratios were significantly (P = .026 and P = .022) higher in cats with increased fPLI, with the area under ROC curve (AUROC) of 68.1% (CI 95%: 53.4%, 82.9%) and 68.6% (CI 95%: 54.0%, 83.2%), respectively. The logistic regression model combining SAA and A/G had AUROC of 75.2% (CI 95%: 62.0%, 88.4%) for identifying cats with increased fPLI. SAA as a sole analyte or combined with A/G had low to moderate accuracy in identifying anorexic, lethargic cats with increased fPLI. Serum albumin, globulin, and Hp concentrations had no discriminatory potential in these cats.

Acute phase proteins in cats: Diagnostic and prognostic role, future directions, and analytical challenges

“…In cats, haptoglobin is often quantified using a commercially available multispecies‐specific kit (Tridelta Development Ltd, County Kildare, Ireland) based on a colorimetric assay which can be adapted to any spectrophotometer 23,26,32,33,37,43,58–64 . It is important to highlight that haptoglobin colorimetric assay has been validated only in dogs.…”

“…While SAA concentrations are significantly higher in cats with increased feline pancreatic lipase immunoreactivity (fPLI), SAA measurements alone cannot accurately predict the probability of increased fPLI in cats with clinical signs suggestive of pancreatitis. 43 Nevertheless, the kinetics of SAA were assessed in a cat with pancreatitis. 44 SAA concentrations were increased at the onset of the disease and then gradually decreased during treatment, paralleling the clinical signs.…”

“…In cats, haptoglobin is often quantified using a commercially available multispecies-specific kit (Tridelta Development Ltd, County Kildare, Ireland) based on a colorimetric assay which can be adapted to any spectrophotometer. 23,26,32,33,37,43,[58][59][60][61][62][63][64] Moreover, even when species-specific immunoassays are applied, a lack of concordance due to variations in epitope structure between individuals and even within individuals leads to differences in immunoreactivity in different assays. 65 Other issues, such as Hook's effect, whereby antibody saturation prevents sandwich formation and results in a falsely low concentration of analytes of interest, are further potential frustrations for an investigator.…”