Neutrophil Gelatinase‐Associated Lipocalin in Cats with Naturally Occurring Chronic Kidney Disease

BACKGROUND: Neutrophil gelatinase‐associated lipocalin (NGAL) is a biomarker for the early prediction of renal damage and the progression of chronic kidney disease (CKD) in humans and dogs. HYPOTHESIS: Neutrophil gelatinase‐associated lipocalin also may play a role in the progression of CKD in cats. ANIMALS: Eighty CKD and 18 control cats. METHODS: Cats were categorized into different stages according to the International Renal Interest Society (IRIS) staging system. Urine and plasma samples were collected and tested for NGAL concentrations using an in‐house sandwich ELISA system and urinary NGAL (uNGAL)‐to‐creatinine ratio (UNCR) was determined. Cats in which serum creatinine concentration increased by >0.5 mg/dL from baseline within 30 days were defined as exhibiting progression. RESULTS: The urinary NGAL and UNCR of CKD cats were significantly higher than those of healthy cats (P < .05) and were highly correlated with serum creatinine concentration. The area under the receiver operating characteristic curve (AUROC) for uNGAL, when predicting the progression of CKD, was 0.71 and the best cutoff value was 2.06 ng/mL with a sensitivity of 76.9% and a specificity of 75%. The AUROC for UNCR when predicting the progression of CKD was 0.79 and the best cutoff value was 4.08 × 10(−6) with a sensitivity of 76.9% and specificity of 79.2%. Cats with UNCR values higher than their cutoffs experienced significantly faster deterioration with a median of 19 days. CONCLUSIONS: Both urinary NGAL and UNCR are useful markers for the prediction of CKD progression in cats.