Information re-verified on March 8, 2021
Updated on March 6, 2020.
Updated on March 6, 2020.
You may have heard about a relatively new test that may be able to detect Chronic Kidney Disease (CKD) earlier than conventional tests in cats and dogs. The test measures the blood levels of a substance called Symmetric Dimethylarginine (SDMA), a byproduct which results from the enzymatic breakdown of certain proteins. SDMA is normally removed from the bloodstream by healthy kidneys. The feedback we've received from veterinarians who are leaders in the field of Feline Chronic Kidney Disease research is that SDMA measurement still needs more validation work, but that it may be a very useful diagnostic tool when utilized in addition to creatinine measurement, especially in older cats that are losing muscle mass.* One concern regarding the SDMA test is that it may appear to perform better than creatinine, but that it actually may perform very similarly depending on the "cut points" i.e.: the points where normal versus abnormal are defined. But the test is showing enough promise that The International Renal Interest Society (IRIS) updated it's guidelines in late 2016 to reflect the fact that SDMA may be a useful diagnostic tool, and published refined staging and treatment guidelines in late 2019 to reflect the ongoing promise of the test. IRIS is the gold standard for Chronic Kidney Disease diagnosis and treatment guidelines for cats and dogs; Dr. Jonathan Elliott, a giant in the field, whose research we are proud to be supporting, is on the IRIS board. Here's what they have to say about the SDMA test:
1. Regarding SDMA generally: "Clearly SDMA has utility for the diagnosis and management of dogs and cats with renal disease. But, as with any promising new biomarker, there is a need for additional studies." You can read the full statement here:
2. Regarding the incorporation of SDMA results into CKD staging: "These recommendations are based on current state of knowledge where SDMA appears to be a more sensitive indicator of early stage CKD in the dog and cat. The specificity of SDMA has not been tested in large scale prospective studies to enable all the factors influencing specificity to be understood. We expect these guidelines to be updated with further recommendations that will assist the use of SDMA in the diagnosis and staging of CKD in the future." You can read the full statement, and the latest staging recommendations here.
It is noteworthy that at least one study indicates that SDMA utility may be compromised in diabetic cats but, as noted earlier, SDMA is still at an early stage, and more research is needed.
3. In late 2019, IRIS republished their CKD treatment recommendations with fully integrated recommendations for how to include SDMA results in treatment plans. The recommendations are here.
IDEXX Labs is currently offering this test as part of certain blood panels at no additional charge, so please ask your vet if it could be appropriate for your feline or canine companions.
* Creatinine is a normal by-product of muscle activity, and is normally removed from the body by the kidneys. If muscle is lost, (which often happens in older patients, and in patients with Chronic Kidney Disease), then less creatinine is produced. Therefore, creatinine levels in CKD patients could be falsely low (i.e.: closer to normal) than they would be if muscle mass were normal, thereby giving the impression that they kidneys are functioning better than they really are.
1. Regarding SDMA generally: "Clearly SDMA has utility for the diagnosis and management of dogs and cats with renal disease. But, as with any promising new biomarker, there is a need for additional studies." You can read the full statement here:
2. Regarding the incorporation of SDMA results into CKD staging: "These recommendations are based on current state of knowledge where SDMA appears to be a more sensitive indicator of early stage CKD in the dog and cat. The specificity of SDMA has not been tested in large scale prospective studies to enable all the factors influencing specificity to be understood. We expect these guidelines to be updated with further recommendations that will assist the use of SDMA in the diagnosis and staging of CKD in the future." You can read the full statement, and the latest staging recommendations here.
It is noteworthy that at least one study indicates that SDMA utility may be compromised in diabetic cats but, as noted earlier, SDMA is still at an early stage, and more research is needed.
3. In late 2019, IRIS republished their CKD treatment recommendations with fully integrated recommendations for how to include SDMA results in treatment plans. The recommendations are here.
IDEXX Labs is currently offering this test as part of certain blood panels at no additional charge, so please ask your vet if it could be appropriate for your feline or canine companions.
* Creatinine is a normal by-product of muscle activity, and is normally removed from the body by the kidneys. If muscle is lost, (which often happens in older patients, and in patients with Chronic Kidney Disease), then less creatinine is produced. Therefore, creatinine levels in CKD patients could be falsely low (i.e.: closer to normal) than they would be if muscle mass were normal, thereby giving the impression that they kidneys are functioning better than they really are.
Update--March 7, 2019:
A study published on February 21, 2019 which examined Glomerular Filtration Rate (GFR)* in 97 dogs, concluded that the overall performance of creatinine and SDMA, as markers of reduced GFR were similar. But the study also states that use of SDMA as an adjunct to creatinine may provide additional value for diagnosis of decreased GFR. More research is warranted. Pelander L, Häggström J, Larsson A, et al. Comparison of the diagnostic value of symmetric dimethylarginine, cystatin C, and creatinine for detection of decreased glomerular filtration rate in dogs. J Vet Intern Med. 2019; 1-10. https://doi.org/10.1111/jvim.15445
* Glomerular filtration rate (GFR) is the volume of fluid filtered by the kidneys over a specified period of time, and is directly proportional to kidney function i.e.: higher GFR equals more kidney function, lower GFR equals less kidney function.
A study published on February 21, 2019 which examined Glomerular Filtration Rate (GFR)* in 97 dogs, concluded that the overall performance of creatinine and SDMA, as markers of reduced GFR were similar. But the study also states that use of SDMA as an adjunct to creatinine may provide additional value for diagnosis of decreased GFR. More research is warranted. Pelander L, Häggström J, Larsson A, et al. Comparison of the diagnostic value of symmetric dimethylarginine, cystatin C, and creatinine for detection of decreased glomerular filtration rate in dogs. J Vet Intern Med. 2019; 1-10. https://doi.org/10.1111/jvim.15445
* Glomerular filtration rate (GFR) is the volume of fluid filtered by the kidneys over a specified period of time, and is directly proportional to kidney function i.e.: higher GFR equals more kidney function, lower GFR equals less kidney function.
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