From the Guidelines
The SDMA blood test is a crucial biomarker for early detection of kidney disease, offering significant advantages over traditional kidney function tests, such as creatinine, by detecting kidney dysfunction earlier and being less affected by muscle mass. SDMA (Symmetric Dimethylarginine) is a methylated form of arginine that increases in the bloodstream when kidney function declines, as it is primarily eliminated through renal filtration. The key significance of SDMA is its ability to detect kidney dysfunction earlier than conventional tests like creatinine, potentially identifying kidney disease when 25-40% of function is lost, compared to creatinine which typically only shows abnormalities after 75% of kidney function is compromised 1.
Key Points of SDMA Blood Test
- SDMA is less affected by muscle mass than creatinine, making it more reliable for assessing kidney function in elderly patients, those with muscle wasting conditions, or animals of different sizes and breeds.
- The test is particularly useful in monitoring chronic kidney disease progression, evaluating kidney function in patients with comorbidities, and assessing renal health before administering potentially nephrotoxic medications.
- For optimal kidney health assessment, SDMA should be used alongside other renal parameters like creatinine, BUN, and urinalysis rather than in isolation, as recommended by guidelines for chronic kidney disease evaluation, classification, and stratification 1.
Clinical Application of SDMA
- Clinicians should consider using SDMA as part of a comprehensive approach to assessing kidney function, especially in cases where creatinine may not provide an accurate picture of renal health.
- The use of SDMA can help in the early detection and management of kidney disease, potentially improving patient outcomes by preventing or delaying the progression of kidney disease and its associated complications.
From the Research
Significance of SDMA Blood Test
The SDMA (Symmetric Dimethylarginine) blood test is a valuable tool in assessing kidney function, particularly in the early detection of chronic kidney disease (CKD) in cats and dogs. The test measures the levels of SDMA in the blood, which is a biomarker that increases with decreased glomerular filtration rate (GFR) 2, 3, 4.
Key Findings
- SDMA is a more sensitive biomarker than serum creatinine concentration (sCr) for assessing renal dysfunction, allowing for earlier detection of CKD 2, 4.
- SDMA concentrations increase above the reference interval with smaller reductions in GFR rate than does creatinine, making it a useful tool for diagnosing early-stage CKD 3.
- Evaluation of both SDMA and creatinine is recommended for diagnosis and monitoring of animals with CKD 3.
- SDMA is unaffected by lean body mass, making it a more reliable biomarker than creatinine in certain cases 4.
Comparison with Creatinine
- SDMA has higher sensitivity than sCr in detecting reduced renal function, but lower specificity and positive predictive value 2, 5.
- Creatinine had higher specificity than SDMA in some studies, but SDMA was still found to be a reliable marker for identifying decreased GFR 5.
Clinical Applications
- The SDMA test can be used to diagnose CKD in cats and dogs, particularly in the early stages of the disease 2, 3, 4.
- SDMA can also be used to monitor the progression of CKD and the effectiveness of treatment 3, 4.
- The test has been incorporated into the International Renal Interest Society (IRIS) guidelines for diagnosing, staging, and treating CKD in cats and dogs 3, 4.