Natalie C Finch1, Harriet M Syme2, Jonathan Elliott3. 1. 1 Bristol Renal, University of Bristol, Bristol, UK. 2. 2 Department of Clinical Science and Services, Royal Veterinary College, Hawkshead Lane, Hatfield, UK. 3. 3 Department of Comparative Biomedical Sciences, Royal College Street, London, UK.
Abstract
OBJECTIVES: The aim of this study was to describe the variability in renal function markers in non-azotaemic and azotaemic cats, and also the rate of change in the markers. METHODS: Plasma creatinine concentration and its reciprocal, glomerular filtration rate (GFR) and urine specific gravity (USG) were studied as markers of renal function in client-owned cats. GFR was determined using a corrected slope-intercept iohexol clearance method. Renal function testing was performed at baseline and a second time point. The within-population variability (coefficient of variation; CV%) was determined at the baseline time point. Within-individual variability (CV%) and rate of change over time were determined from the repeated measurements. RESULTS: Twenty-nine cats were included in the study, of which five had azotaemic chronic kidney disease. The within-individual variability (CV%) in creatinine concentration was lower in azotaemic cats than in non-azotaemic cats (6.81% vs 8.82%), whereas the within-individual variability in GFR was higher in azotaemic cats (28.94% vs 19.98%). The within-population variability was greatest for USG (67.86% in azotaemic cats and 38.00% in non-azotaemic cats). There was a negative rate of change in creatinine concentration in azotaemic and non-azotaemic cats (-0.0265 and -0.0344 µmol/l/day, respectively) and a positive rate of change of GFR in azotaemic and non-azotaemic cats (0.0062 and 0.0028 ml/min/day, respectively). CONCLUSIONS AND RELEVANCE: The within-individual variability data suggest creatinine concentration to be the more useful marker for serial monitoring of renal function in azotaemic cats. In contrast, in non-azotaemic cats, GFR is a more useful marker for serial monitoring of renal function. The majority of cats with azotaemic CKD did not have an appreciable decline in renal function during the study.
OBJECTIVES: The aim of this study was to describe the variability in renal function markers in non-azotaemic and azotaemiccats, and also the rate of change in the markers. METHODS: Plasma creatinine concentration and its reciprocal, glomerular filtration rate (GFR) and urine specific gravity (USG) were studied as markers of renal function in client-owned cats. GFR was determined using a corrected slope-intercept iohexol clearance method. Renal function testing was performed at baseline and a second time point. The within-population variability (coefficient of variation; CV%) was determined at the baseline time point. Within-individual variability (CV%) and rate of change over time were determined from the repeated measurements. RESULTS: Twenty-nine cats were included in the study, of which five had azotaemicchronic kidney disease. The within-individual variability (CV%) in creatinine concentration was lower in azotaemiccats than in non-azotaemiccats (6.81% vs 8.82%), whereas the within-individual variability in GFR was higher in azotaemiccats (28.94% vs 19.98%). The within-population variability was greatest for USG (67.86% in azotaemiccats and 38.00% in non-azotaemiccats). There was a negative rate of change in creatinine concentration in azotaemic and non-azotaemiccats (-0.0265 and -0.0344 µmol/l/day, respectively) and a positive rate of change of GFR in azotaemic and non-azotaemiccats (0.0062 and 0.0028 ml/min/day, respectively). CONCLUSIONS AND RELEVANCE: The within-individual variability data suggest creatinine concentration to be the more useful marker for serial monitoring of renal function in azotaemiccats. In contrast, in non-azotaemiccats, GFR is a more useful marker for serial monitoring of renal function. The majority of cats with azotaemic CKD did not have an appreciable decline in renal function during the study.
Authors: John C Rowe; Jessica A Hokamp; Jessica N Braatz; John R Freitag-Engstrom; Nicole L Stephens; Dennis J Chew; Catherine Langston; Adam J Rudinsky Journal: J Vet Diagn Invest Date: 2021-03-01 Impact factor: 1.279