Internal Medicine Journal Watch
Michael Goldstein, DVM, Diplomate ACVIM
Central Toronto Veterinary Referral/Emergency Clinic
Comparison of Serum Concentrations of Symmetric Dimethylarginine and Creatinine as Kidney Function Biomarkers in Cats with Chronic Kidney Disease
J.A. Hall, M. Yerramilli, E. Obare, M. Yerramilli, and D.E. Jewell J Vet Intern Med 2014;28:1676–1683
Symmetric dimethylarginine (SDMA) is a bi-product of L-arginine metabolism, has been shown to be an accurate and precise biomarker for calculating estimated glomerular filtration rate (GFR) in humans, as well as a more sensitive biomarker than serum creatinine concentration (sCr) for assessing renal dysfunction.
The purpose of this retrospective study was to report on the utility of measuring serum SDMA concentrations in cats for detection of chronic kidney disease (CKD) before diagnosis by conventional measurement of sCr.
The study included 21 CKD cats and 21 healthy geriatric cats from the same colony. Fifteen of the CKD cats were persistently azotemic for ≥3 months, 4 cats were nonazotemic cats with a measured GFR that was >30% decreased from median GFR of normal cats, and 2 cats were nonazotemic cats with calcium oxalate kidney stones.
Serum SDMA and sCr concentrations were significantly correlated to GFR. SDMA became increased before sCr in 17/21 cats (mean, 17.0 months; range, 1.5– 48 months). Serum SDMA had higher sensitivity (100%) compared with sCr (17%), but lower specificity (91% versus 100%) and positive predictive value (86% versus 100%).
- This study demonstrated that a normal serum SDMA concentration was excellent at reassuring the clinician and owner that the patient does not have CKD.
- If the serum SDMA concentration is increased this could be the result of a false positive and further monitoring or evaluation may be recommended.
- Conversely, a normal sCr concentration is poor at reassuring the clinician and owner that the patient does not have CKD.
- However, a patient with an elevated sCR is excellent at informing the clinician and owner that the patient does have CKD.
Important to remember is that all this is based on assuring that pre-renal causes of decreased GFR and causes of acute kidney injury have been eliminated.
There is substantial evidence to support initiating renal diets in cats with IRIS CKD stage 2 or higher and this is considered the current standard of care. Dietary modifications include decreased protein, phosphorus, and sodium content; increased water soluble vitamins and fiber content; increased caloric density; and additional n-3 fatty acids, antioxidants, and potassium
According to the IRIS staging of CKD, cats with stage 1 and 2 CKD may have sCr in the normal reference range. As such, serial monitoring of sCR may delay the onset of dietary management of some cats with early CKD. The use of a serum SDMA to help identify cats with CKD earlier in the disease may result in the slowing the progression of the kidney disease and ameliorate clinical and biochemical consequences of CKD. At this time more data is required to substantiate this claim and if this will have a clinical impact or not.
If you have any questions about SDMA, chronic kidney disease or any other topics please do not hesitate to contact me at 416-784-4444 or firstname.lastname@example.org
Posted by: Michael Goldstein, DVM, Diplomate ACVIM
Categorised as: Blog & Articles
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