Stand number 70-73
This article is sponsored content brought to you by IDEXX.
IDEXX SDMA® offers some distinct advantages that every veterinarian should understand
In April 2018, IDEXX SDMA® has become available on the Catalyst Chemistry as an in-house test. Here we review its advantages and interpretation.
SDMA (symmetric dimethylarginine) is a reliable biomarker for assessing kidney function, because it has been established as an accurate marker of GFR. Produced during the metabolism of Arginine, SDMA is released into circulation when intracellular protein is broken down. Once in circulation, it is almost exclusively eliminated by the kidneys. Like any other parameter, SDMA should be used as a complement to other renal markers and interpreted considering the patients’ history and physical exam.
Crucially, it does offer several advantages when compared to creatinine as the most common marker used in practice:
1. SDMA is more tightly related to GFR than creatinine*.
2. SDMA increases earlier than creatinine as GFR falls (reliably at 40% loss of renal mass, and as early as 25% loss as opposed to 75% loss for creatinine)*.
3. SDMA is more specific than creatinine, as it is not affected by alterations in lean body mass*.
Because of these advantages, it is vital that you DO NOT ignore an increased SDMA result, as it reflects a reduced GFR and requires investigation. In the majority cases it is indicative of kidney disease. While this can often be explained by chronic kidney disease, an elevated SDMA result can also occur with pre- or post-renal disease.
It is important to remember that a persistently increased SDMA level represents an opportunity to evaluate a patient to determine if there is something affecting renal function which can be managed.
The physical examination is valuable in these cases as it facilitates the identification of dehydration or signs of post-renal disease. The next step with an elevated SDMA result should always be a complete urinalysis to look for other signs of urinary tract disease.
In patients with a mild increase in SDMA (15–19 ug/dL), no clinical signs of kidney disease and unremarkable urine, repeat the SDMA test in 2-4 weeks time. If the SDMA remains increased, or there are clinical signs of disease, or the increase in SDMA is more marked, further investigation is warranted. This includes blood pressure measurement, a UPC ratio, possibly a urine culture or leptospiral testing, and perhaps an abdominal ultrasound.
Significantly, the International Renal Interest Society has incorporated IDEXX SDMA® into its diagnostic, staging and management scheme for CKD.
IDEXX SDMA® will allow practitioners to more simply identify kidney disease, including IRIS Stage 1 CKD. This diagnosis will allow practitioners to take steps to manage these patients appropriately, protect the kidneys and potentially slow disease progression.
Management should include treating anything found during the investigation, free access to water, and the use of a high-quality diet with appropriate phosphate levels. It is important to take care when using nephrotoxic drugs – these may still be indicated in some cases – such as a CKD dog or cat with osteoarthritis.
Where NSAIDs are required for quality of life, use the lowest dose possible and potentially a combination with other drugs. Care should be taken with anaesthesia to ensure patients are hydrated and hypotension is avoided. In cases with kidney disease identified, more frequent monitoring may be required.
Ultimately, creatinine is one of the most commonly tested analytes in small animal medicine. So if you are going to include creatinine in your biochemistry panel, why not include IDEXX SDMA® as an essential part of the modern chemistry panel? Contact IDEXX on 1300 44 33 99 or email IDEXX-ANZ-Sales@idexx.com.
* Data on file at IDEXX Laboratories, Westbrook, Mainew