Plasma symmetric dimethylarginine and creatinine concentrations and glomerular filtration rate in cats with normal and decreased renal function

Background Glomerular filtration rate (GFR) is the gold standard in assessing renal function but is impractical. Serum creatinine (sCr) has limited sensitivity in identifying early chronic kidney disease (CKD), whereas symmetric dimethylarginine (SDMA) has been commercialized as more accurate biomarker. Studies comparing SDMA and sCr with GFR in cats are limited. Objectives To further investigate the diagnostic performance of SDMA in nonazotemic and azotemic cats. Animals Forty-nine client-owned cats: 17 cats with CKD, 15 cats with diabetes mellitus (DM), and 17 healthy cats. Methods Retrospective study using spare blood samples from cats with documented sCr and GFR results for SDMA analysis. Diagnostic performances of SDMA and sCr were evaluated using correlation coefficients, sensitivities, specificities, and receiver operator characteristic curves. Results Compared to healthy cats and cats with DM, CKD cats had significantly higher SDMA(plasma) (26.7 +/- 9.9 mu g/dL) and sCr (249.7 +/- 71.6 mu mol/L [2.8 +/- 0.8 mg/dL]; both P < .001) values. SDMA(plasma) (tau(B) = -0.57; P < .001) and sCr (tau(B) = -0.56; P < .001) were significantly correlated with GFR. SDMA(plasma) (tau(B) = 0.52; P < .001) had a significant relationship with sCr. SDMA(plasma) and sCr had similar sensitivity (76%-94% and 71%-88%, respectively) in detecting reduced renal function. Creatinine had higher specificity (94%-96%) than SDMA(plasma) (75%-76%) (P < .05). Conclusion and Clinical Importance In this study of azotemic and nonazotemic cats, SDMA was a reliable marker to identify decreased GFR. However, superiority of SDMA over sCr could not be confirmed.