Variability of Symmetric Dimethylarginine in Apparently Healthy Dogs

Abstract

BackgroundSymmetric dimethylarginine (SDMA) is a screening tool for early kidney dysfunction and monitoring treatment in cases of chronic kidney disease (CKD). There are no current studies describing the suitability of this test for use with published population‐based reference intervals.Hypothesis/ObjectivesTo determine the components of biological variability, the index of individuality (IOI), the critical difference between sequential measurements (C D) and the number of measurements required to assess the homeostatic set point (HSP), for both SDMA and serum creatinine (sCr), in apparently healthy dogs.AnimalsTwenty apparently healthy adult dogs owned by clients or staff at a veterinary teaching hospital.MethodsProspective, observational study. Blood was collected from each dog on 9 occasions, and SDMA and sCr were measured in duplicate using commercially available assays.ResultsSDMA and sCr had intermediate and low IOI values of 0.87 and 0.28, respectively. The C D of SDMA and sCr, was 1.34 µg/dL and 0.89 µmol/L, respectively. The sample numbers required for estimation of an individual's HSP (with 90 and 95% CI) for SDMA and sCr were 8 and 45, and 2 and 12 sequential measurements, respectively.Conclusions and Clinical ImportanceBased on our findings, in comparison to sCr, SDMA is better suited for use with population‐based reference intervals. False‐negative test results could occur when comparing a single test result from an individual to such intervals. Ideally C D should be used with sequential measurements.

Serum Symmetric Dimethylarginine as an Early Marker of Excretory Dysfunction in Canine Leishmaniosis(L. infantum)Induced Nephropathy

“…For dogs with no suspicion of renal disease, repeating single SDMA measurement between 15 and 19 μ g/dL is recommended [ 30 ], but this was not possible due to the retrospective nature of our study. Some authors also have suggested that young dogs and Greyhounds might have a URL higher than 14 μ g/dL [ 18 , 36 ], and in a recent study [ 42 ], the mean SDMA concentration of 20 apparently healthy dogs (12.7 μ g/dL) was situated in the top quarter of the population-based reference interval established by IDEXX Laboratories. Therefore, in order to reduce the number of dogs with doubtful SDMA classification (range 15–19 μ g/dL), we decided to use SDMA >19 μ g/dL as a clinical decision cut-off value for both control dogs and dogs with leishmaniosis to increase the specificity of the test in spite of a decrease in sensitivity.…”

Response to letter to editor regarding Variability of symmetric dimethylarginine in apparently healthy dogs

“…In a recent publication, 1 we made a mathematical error in the calculation of C D and RCV, and hence, we have recalculated these values for the study cohort means for symmetric dimethylarginine (SDMA) and creatinine and found them to be 5.98 μg/dL (RCV of 47%) and 22.8 μmol/L (RCV 23.7%), respectively. It is of note that these recalculated C D and RCV values indicate greater biological and analytical variability for these variables.…”

Changes in renal parameters and their association with subclinical vector-borne infections in Bernese Mountain dogs

“…Not being fasted and higher muscle mass are possible reasons for increased creatinine as well, however, this would also apply for the control dogs. Determination of symmetric dimethylarginin (SDMA) would have helped to exclude this influence but was not available when the study was performed [20]. Therefore, it is possible that some of the dogs would not have been classified as dogs with renal disease if repeated measurements of creatinine and USG or measurement of glomerular filtration rate (GFR) were performed to confirm the presence of renal disease.…”