Longitudinal evaluation of symmetric dimethylarginine and concordance of kidney biomarkers in cats and dogs

Symmetric dimethylarginine (SDMA) is a sensitive surrogate marker for glomerular filtration rate; however, there are uncertainties as to how to interpret mild increases (SDMA 15-19 mu g/dL). This descriptive study used retrospective data to evaluate whether cats or dogs that had initial SDMA values (at T0) within the reference interval followed by an increased SDMA (at T1) had persistently increased SDMA (at T2; measured from 14 days to 18 months following T1; Persistence Cohort), and if and when cats or dogs with persistently increased SDMA had increased creatinine up to 24 months (Concordance Cohort). The Persistence Cohort included 16,670 cats and 16,712 dogs. If SDMA at T1 was 15-19 mu g/dL, the probability of persistence was 53% for cats and 42% for dogs, while creatinine was concurrently increased in 20% of cats and 18% of dogs. For comparison, if SDMA was not increased at T1 the probability of increased SDMA at recheck was only 20% for cats and 9% for dogs. For cats and dogs with a T1 SDMA of 15-19 mu g/dL and with persistent increases at T2, the probability of increased creatinine at T1 was 20% for cats and 18% for dogs, rising to 61% and 55%, respectively, by 24 months. When SDMA at T1 was >25 mu g/dL, creatinine was increased in 93% of cats and 92% of dogs by 24 months. Mildly increased SDMA results may provide an opportunity to identify some cats and dogs earlier in their kidney disease.