Analytical validation, reference interval determination, and diagnostic performance of plasma symmetric dimethylarginine in cattle.

Plasma SDMA at a cut-off of 160 μg/L shows high sensitivity and specificity for diagnosing kidney disease in cattle.

This study evaluated plasma symmetric dimethylarginine (SDMA) as a biomarker for kidney disease in cattle, addressing the known limitations of traditional markers such as serum urea and creatinine, which have poor sensitivity and specificity in this species. The researchers performed a partial analytical validation of SDMA measurement using a benchtop analyzer with bovine plasma, assessing short- and long-term imprecision, linearity, and stability. A reference interval was established in 199 healthy cattle (53 male and 96 female beef cattle, and 50 female dairy cows) following ASVCP guidelines, yielding a reference interval of 60–160 μg/L. No significant differences were identified based on sex, breed, or diet. Diagnostic performance was evaluated by comparing healthy animals to 27 azotemic cows with confirmed kidney disease. Using 160 μg/L as the cut-off (upper reference limit), SDMA demonstrated a sensitivity of 0.85 and specificity of 0.98, with strong overall diagnostic performance supported by ROC curve analysis. The analytical performance of the assay was deemed acceptable for clinical use. These findings suggest that plasma SDMA is a promising and analytically reliable biomarker for the diagnosis of kidney disease in cattle, potentially superior to conventional markers. However, the authors acknowledge that the study population was limited in size and diversity, and that further prospective studies are needed to confirm these findings across broader bovine populations and clinical contexts before widespread implementation is recommended.

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