Diagnostic value of reticulocyte indices for the assessment of the iron status of cats with chronic kidney disease

Abstract

Background: Reticulocyte indices have been suggested as alternatives to transferrin saturation (TSAT) for iron status assessment in humans and dogs but they have not been evaluated thoroughly in cats. Objectives: To assess the value of the reticulocyte indices for the diagnosis of iron deficiency in cats with chronic kidney disease (CKD) and chronic hematuria associated with subcutaneous ureteral bypasses (SUBs). Animals: Sixty-four cats: 16 healthy, 14 CKD without SUB, and 34 CKD with SUB. Methods: Prospective observational cross-sectional study of cats presented for routine nephrology visits. Primary outcomes included assessment of the diagnostic values of erythrocyte indices (mean corpuscular volume, hemoglobin, and hemoglobin concentration: MCV, MCH, and MCHC) and reticulocyte indices (mean corpuscular volume, MCVr; corpuscular hemoglobin, CHr), using TSAT as reference. Results: Iron deficiency was diagnosed in 9/64 cats (14%). A receiver-operating characteristic curve analysis yielded a moderate discriminatory value for CHr in this diagnosis: area under the curve [AUC] =.75 (95% confidence interval, 0.48-0.89); P =.006; sensitivity 67%, specificity 82% for a cutoff of 15.9 pg. This compared favorably to MCVr (AUC =.63; P =.29), MCV (AUC =.58; P =.45), MCH (AUC =.64; P =.19), and MCHC (AUC =.7; P =.03). Conclusion and Clinical Importance: CHr added moderate value to the diagnosis of iron deficiency in cats with CKD.