As a foundation for systemic health, the kidneys support nearly every organ and process within the body. A few of their key roles include blood pressure management, red blood cell production, hormonal balance, and clearance of metabolic byproducts and toxins.²⁵ While renal screening diagnostics are used extensively for the monitoring and management of CKD, they can do so much more by informing the veterinarian on overall multi-system function and the possibility of injury or illness affecting the kidneys and other vital organs.

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Abnormal Results Facilitate Appropriate Investigation

When screening results are found to be outside the normal reference interval, they can indicate a reduction in kidney function, injury to the kidney or another organ, disruption in metabolism, or various other processes that threaten homeostasis, long-term health, or a patient's ability to tolerate anesthesia. A change to a renal value or values such as blood urea nitrogen, creatinine, and SDMA may not offer a definitive clinical diagnosis, but it does wave the red flag needed to decide if further investigation is warranted.

For example, vector-borne diseases may cause obvious clinical signs, or they may go entirely undetected for extended periods of time. Because they are central to systemic health, the kidneys are often concurrently affected by infectious disease, and SDMA can provide an early indication of kidney function decline. An elevation in SDMA, with or without clinical symptoms, could give the veterinarian the heads-up they need to investigate vector-borne disease as an underlying or hidden issue, especially in endemic regions or in cases where the origin of the pet is unknown.^19,20

Renal Assessment Impacts Anesthetic Choices and Safety

Veterinarians know all too well that patients tend to mask underlying disease for as long as possible. In a clinical study, diagnostic testing (consisting of a chemistry panel, complete blood count, SDMA test, urinalysis and TT4 {in cats 7+ years of age}) in more than 200,000 outwardly healthy pets uncovered clinically relevant abnormalities in 1 in 5 mature adult dogs (aged 4-8 years) and 1 in 3 mature adult cats (aged 7-9 years). Because of this, SDMA is particularly useful as it indicates a decline in kidney function earlier than other biomarkers.^1,2,5

This can be especially important when creating the safest possible anesthetic plan for a patient. If there is an indication that the kidneys may not be operating optimally, adjustments can be made to anesthetic choices to help lessen the negative impact on blood pressure.²⁵

Kidney Assessment as a Monitoring and Management Tool for Disease

The results from kidney diagnostics can be used to monitor the improvement and management of infectious and chronic diseases. In the example of vector-borne diseases, SDMA can be useful in long-term monitoring plans as it tends to elevate earlier than other renal biomarkers.^1,2,5 An elevation could indicate a relapse or failure to cure the disease, inciting the veterinarian to take action and, in some cases, save the pet's life.

Monitoring Kidney Function in Dogs

In dogs in endemic areas, studies show a correlation between dogs with positive Lyme or Ehrlichia exposure and an increased risk for CKD.^19,20 By including SDMA in the chemistry profile for dogs with a history of tick exposure, veterinary professionals have additional information to determine how significant the tick exposure may have been and whether to continue monitoring that pet for development or progression of tick-borne disease in the future.

Monitoring Kidney Function in Cats

For cats, SDMA and renal biomarkers are routinely used to monitor progression and make treatment choices in cases of CKD. Two other conditions that warrant SDMA monitoring in felines are hyperthyroidism and retroviral infections—feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV). Hyperthyroidism and retroviruses impact systemic health, including the kidneys.

Many cats with hyperthyroidism have an loss of muscle mass, which can lead to decreased creatinine production and an inaccurate picture of kidney health.^14,15 However, SDMA is less affected by the decrease in lean muscle mass and is, therefore, a better monitoring tool in these patients.^3,15

Earlier diagnosis of concurrent renal disease in cats with hyperthyroidism may have a positive impact on quality of life and survival time. Retroviruses, such as FeLV and FIV, are poorly understood, but veterinarians know they can impact kidney health and that symptoms related to these viruses can be compounded by a decline in kidney function. By detecting kidney dysfunction earlier, veterinary professionals can obtain a clearer picture of disease progression and take steps to support the kidneys.^3,15

The Importance of Kidney Health

When it comes to screening for overall health status, early disease detection, and chronic condition management, the kidneys may very well be the most important organ for veterinarians to keep their eyes on. Not only do kidney diagnostics provide information on the health of the kidneys themselves, but they can provide insight into the overall health of an animal, ultimately leading to better care and treatment.

References: https://www.thevetiverse.com/en/latest/sdma-references/