Objective: To investigate whether chickens (Gallus gallus) have measurable plasma symmetric dimethylarginine (SDMA) and to establish the diagnostic utility of the commercially available immunoassay (IA) for measurement of SDMA.
Animals: 245 chicken hens.
Methods: Blood samples were assessed for renal-focused biochemistry analytes. Plasma SDMA was determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS/MS) and a high-throughput IA. A Passing-Bablok regression was used to compare the results of IA to LC-MS/MS/MS and reference intervals SDMA values were calculated.
Results: The reference interval for plasma SDMA measured by LC-MS/MS/MS is 5.58 to 10.62 μg/dL (range of values, 5 to 15 μg/dL). The concentration of SDMA measured by IA ranged from 1 to 12 μg/dL with a median of 7 μg/dL. Concentrations measured by SDMA-IA demonstrated a low correlation to the SDMA LC-MS/MS reference method. A Passing-Bablok linear regression analysis had a slope of 1.67 (95% CI, 1.35 to 2.14), an intercept of -5.76 (95% CI, -9.90 to -3.35), and a Kendall τ correlation of 0.39.
Clinical relevance: SDMA circulates in chicken plasma and should be investigated as a potential renal biomarker in future studies. Because SDMA-IA exhibits a low correlation to the reference method (LC-MS/MS) future assessments of SDMA in chickens should utilize LC-MS/MS assays and compare them to the reference interval created here.