Relationship between serum iohexol clearance, serum SDMA concentration, and serum creatinine concentration in non-azotemic dogs.

Myles McKenna,Ludovic Pelligand,Rosanne Jepson,Daniel Cotter,Jonathan Elliott

doi:10.1111/jvim.15659

Myles McKenna, Ludovic Pelligand + Show 3 more

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https://doi.org/10.1111/jvim.15659

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Abstract

BackgroundSerum creatinine and symmetric dimethylarginine (SDMA) are used as surrogate markers of glomerular filtration rate (GFR) in clinical practice. Data pertaining to the correlations between GFR, SDMA, and serum creatinine in client‐owned dogs are limited.ObjectivesTo describe the relationship between GFR, SDMA, and serum creatinine in a population of client‐owned dogs, and to compare clinical utility of SDMA to GFR estimation for detecting pre‐azotemic chronic kidney disease.AnimalsMedical records of 119 dogs that had GFR estimation performed via serum iohexol clearance between 2012 and 2017.MethodsProspective study using archived samples. GFR, SDMA, and serum creatinine results were reviewed and submitting practices contacted for outcome data. All dogs included in the study population were non‐azotemic. Correlations between GFR, SDMA, and serum creatinine were determined by regression analysis. Sensitivity, specificity, and positive and negative likelihood ratios of different cutoffs for SDMA and serum creatinine for detecting decreased GFR were calculated, using a 95% confidence interval.ResultsSerum creatinine and SDMA were moderately correlated with GFR (R2 = 0.52 and 0.27, respectively, P < .0001) and with each other (R2 = 0.33, P < .0001). SDMA >14 μg/dL was sensitive (90%) but nonspecific (50%) for detecting a ≥40% decrease in GFR. Optimal SDMA concentration cutoff for detecting a ≥40% GFR decrease was >18 μg/dL (sensitivity 90%, specificity 83%).Conclusions and Clinical ImportanceIn non‐azotemic dogs being screened for decreased renal function, using a cutoff of >18 μg/dL rather than >14 μg/dL increases the specificity of SDMA, without compromising sensitivity.

Highlights

Glomerular filtration rate (GFR) estimation is regarded as the gold standard method for assessing renal function, as it is directly proportional to renal mass.[1]
glomerular filtration rate (GFR) estimation is the gold standard for assessing renal function, measurement of serum creatinine, a surrogate marker of GFR, remains the main means of assessing renal function in dogs in clinical practice.[14]
The aim of this study was to describe the relationship between GFR, symmetric dimethylarginine (SDMA), and serum creatinine in a population of client-owned dogs presenting to both referral and first-opinion practice and to compare the clinical utility of SDMA to the gold standard of GFR estimation via serum iohexol clearance for the detection of pre-azotemic chronic kidney disease (CKD)

Summary

| INTRODUCTION

Glomerular filtration rate (GFR) estimation is regarded as the gold standard method for assessing renal function, as it is directly proportional to renal mass.[1]. Recent studies indicate that symmetric dimethylarginine (SDMA) could be a promising marker of GFR in dogs.[19,20] Symmetric dimethylarginine is produced by the breakdown of proteins, the arginine residues of which have been posttranslationally methylated and is excreted primarily (≥90%) by renal clearance.[21,22] Unlike serum creatinine, SDMA is unaffected by lean body mass.[16] Symmetric dimethylarginine has an exponential relationship with GFR but could be a more sensitive marker of declining GFR than serum creatinine.[19] A caveat is that data pertaining to the effects of concurrent disease on SDMA remain somewhat limited. The aim of this study was to describe the relationship between GFR, SDMA, and serum creatinine in a population of client-owned dogs presenting to both referral and first-opinion practice and to compare the clinical utility of SDMA to the gold standard of GFR estimation via serum iohexol clearance for the detection of pre-azotemic CKD

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION