Urine and plasma metanephrine concentrations in cats with chronic kidney disease: characterization and correlation with biomarkers of renal function

BACKGROUND: The role of the autonomic nervous system in the pathophysiology of chronic kidney disease (CKD) in cats is currently unknown. HYPOTHESIS/OBJECTIVES: To describe urine and plasma metanephrines concentration in cats with CKD and their correlation with biomarkers of kidney function. ANIMALS: Fifty-nine cats were recruited and divided into 3 groups: cats with CKD (n = 28), healthy cats (HC) (n = 21), and cats with nonadrenal, non-kidney-related chronic illness (n = 10). METHODS: A cross-sectional study was performed in cats recruited from a veterinary teaching hospital. Metanephrine and normetanephrine concentrations were measured in urine (U-MN/NMN) and plasma (P-MN/NMN) by liquid chromatography tandem mass spectrometry. Data were correlated with biomarkers of kidney function measured in the same time-point sample. RESULTS: The CKD group had significantly higher P-NMN (median, 14.20; min-max, 5.65-34.09 nmol/L) than the HC group (7.03; 5.19-13.03 nmol/L). P-MN concentrations correlated with the urinary protein-creatinine ratio (UPCR) (r = 0.528, P = .017). P-NMN correlated with symmetric dimethylarginine (SDMA) (r = 0.604, P = .006), serum creatinine (r = 0.488, P = .029) and UPCR (r = 0.445, P = .049). U-MN:urine creatinine concentration (UCreat) ratio correlated with UPCR (r = 0.683, P < .001) and urine specific gravity (r = -0.397), P < .001). U-NMN:UCreat ratio correlated with SDMA (r = 0.558, P = .007), serum phosphate (r = 0.561, P = .005) and UPCR (r = 0.494, P = .017). CONCLUSION AND CLINICAL IMPORTANCE: There is evidence of sympathetic nervous system dysfunction in cats with CKD.