Association of Serum Symmetric Dimethylarginine Concentrations and Inflammation in Cats

Abstract

Background

Serum symmetric dimethylarginine (SDMA) concentrations are higher in some hyperthyroid cats with normal renal function, presumably due to increased protein catabolism.

Objectives

To investigate if SDMA is higher in cats with inflammation (defined as elevated serum amyloid A [SAA]).

Animals

Twenty-eight cats: 12 with elevated SAA concentrations (> 3.9 μg/mL) and 16 with normal SAA.

Methods

Retrospective case control study. Cats presenting to a referral institution between 2016 and 2022 with a documented SAA were identified. Individuals with renal and extrarenal factors known to affect SDMA were excluded. SDMA was measured from stored serum samples. Comparisons were made using the Mann–Whitney U test, and correlations assessed using Spearman's correlation coefficient. Data are presented as median [minimum–maximum].

Results

SDMA was not significantly different between cats with elevated SAA and normal SAA (11 [5–17] μg/dL vs. 13 [9–21] μg/dL, respectively; p = 0.28). There was no correlation between SDMA and SAA (r_s = −0.105; p = 0.594) or serum TT4 concentrations (r_s = −0.023; p = 0.906). No difference in age or USG was present between elevated SAA and normal SAA groups (p = 0.908 and p = 0.165, respectively). Serum urea and creatinine concentrations were both significantly lower in cats with elevated SAA compared to those with normal SAA (6.3 [3.6–8.8] mmol/L vs. 8.4 [6.2–10.5] mmol/L; p = 0.008, and 96 [62–129] μmol/L vs. 118 [90–147] μmol/L; p = 0.008, respectively).

Conclusions and Clinical Importance

SDMA might be a more representative biomarker of GFR during inflammatory states, provided other confounding factors that affect SDMA are eliminated.