Evaluation of symmetric dimethylarginine in cats with acute kidney injury and chronic kidney disease

Abstract

Background: Serum symmetric dimethylarginine (SDMA) concentrations are considered a biomarker for renal dysfunction in dogs and humans with acute kidney injury (AKI). No studies have assessed SDMA in feline AKI.

Hypothesis/objectives: SDMA correctly identifies cats with azotemic AKI as well as cats with chronic kidney disease (CKD).

Animals: Fifteen control cats, 22 with AKI, 13 with acute on chronic-AKI (AoC-AKI) and 19 with CKD.

Methods: Retrospective study. Cats with azotemia (serum creatinine concentrations >1.7mg/dL) were defined as having AKI or CKD based on history, clinical signs, clinicopathological findings and diagnostic imaging, and classified using the IRIS grading/staging systems. Control cats had no evidence of azotemia or systemic inflammation, urine specific gravity >1.035 and negative urine culture. Serum SDMA concentrations were compared between groups, with correlations assessed using Spearman’s correlation coefficient. Data are presented as median [range].

Results: Serum SDMA concentrations were 11 (8-21) μg/dL, 36 (9-170) μg/dL, 33 (22-75) μg/dL and 25 (12-69) μg/dL in control, novel AKI, AoC-AKI and CKD cats. Serum SDMA concentrations were significantly higher in cats with novel AKI (P<0.001), AoC-AKI (P<0.001) and CKD (P<0.01) compared to controls. Serum SDMA concentrations were significantly higher in cats with more advanced AKI (higher IRIS grade) compared to less severe AKI. Serum creatinine and SDMA concentrations showed a significant correlation in cats with novel AKI (rs= 0.826, n=22); P <0.001) and a significant correlation when all cats across all 4 groups were considered together (rs= 0.837, n=69; P <0.001).

Conclusions and clinical importance: Serum SDMA concentrations are elevated in cats with established AKI (novel and AoC) and CKD, providing baseline evidence for SDMA as a biomarker for AKI in cats.