Risk factors and implications associated with ultrasound‐diagnosed nephrocalcinosis in cats with chronic kidney disease

Abstract Background Microscopic nephrocalcinosis is a common pathological feature of chronic kidney disease (CKD) in cats. Detection of macroscopic nephrocalcinosis using ultrasonography and its implications remain unexplored. Objectives Identify risk factors associated with ultrasound‐diagnosed nephrocalcinosis and evaluate the influence of nephrocalcinosis on CKD progression. Animals Thirty‐six euthyroid client‐owned cats with CKD. Methods Prospective cohort study. Cats with CKD with and without ionized hypercalcemia were enrolled for renal ultrasonography. Cats were categorized according to the presence or absence of ultrasound‐diagnosed nephrocalcinosis. Binary logistic regression was performed to identify nephrocalcinosis risk factors. The influence of nephrocalcinosis on CKD progression was assessed using linear mixed models. Results Ultrasound‐diagnosed nephrocalcinosis was evident in 61% of CKD cats overall, with increased prevalence (81%) in those with hypercalcemia. At enrollment, higher blood ionized calcium concentration (odds ratio OR, 1.27 per 0.1 mg/dL; P = .01), plasma phosphate concentration (OR, 1.16 per 0.1 mg/dL; P = .05), plasma creatinine concentration (OR, 1.29 per 0.1 mg/dL; P = .02) and alanine aminotransferase activity (OR, 2.08 per 10 U/L; P = .04) were independent nephrocalcinosis risk factors. The rate of change in log‐transformed fibroblast growth factor‐23 differed significantly between groups ( P = .04). Cats with CKD and nephrocalcinosis had increasing plasma creatinine concentrations (.03 ± .01 mg/dL/month; P = .04) and phosphate concentrations (.06 ± .02 mg/dL/month; P < .001) and decreasing body weight (.02 ± .01 kg/month; P < .001) over time. Conclusions and Clinical Importance Nephrocalcinosis is prevalent in cats with CKD, especially in those with hypercalcemia. This pathological feature appears to be associated with CKD progression in cats.