Urine hemojuvelin in cats with naturally occurring kidney disease

BACKGROUND: Soluble‐type hemojuvelin in serum and urine has been shown to be a biomarker in humans for chronic kidney disease (CKD) and acute kidney injury (AKI). No similar research has been conducted on cats. OBJECTIVE: Urine hemojuvelin (u‐hemojuvelin) can be used as a clinical indicator for cats with various renal diseases. ANIMALS: Eighteen healthy cats, 10 cats with AKI, 21 cats with acute‐on‐chronic kidney injury (ACKI), and 45 cats with CKD were enrolled. METHODS: The expression profile of u‐hemojuvelin was assessed by Western blot analysis, whereas the u‐hemojuvelin concentration was measured using an in‐house sandwich ELISA. Each cat's u‐hemojuvelin‐to‐creatinine ratio (UHCR) also was determined. RESULTS: Significant differences were found in both u‐hemojuvelin concentration and UHCR between the control cats and the other cats (AKI, CKD, ACKI). Both u‐hemojuvelin and UHCR had high areas under the receiver operator curve (AUROC) for diagnoses of AKI (u‐hemojuvelin, 0.885; UHCR, 0.982), CKD (hemojuvelin, 0.869; UHCR, 0.959), and ACKI (hemojuvelin, 0.910; UHCR, 1). Late stage (International Renal Interest Society, IRIS stages 3 and 4) CKD cats had significantly higher u‐hemojuvelin concentration and UHCR than did early stage cats (IRIS stages 1 and 2). Both u‐hemojuvelin and UHCR were significantly correlated with high blood urea nitrogen, plasma creatinine, and plasma phosphate concentrations and with low hematocrit (Hct), red blood cell (RBC) count, and plasma albumin concentration. The UHCR values were also significantly correlated with white blood cell count in blood. CONCLUSION: Both u‐hemojuvelin and UHCR potentially can serve as diagnostic indicators for a range of renal diseases in cats.