Here, we'll explore some of the most common cases of kidney injury and how testing with the novel biomarker cystatin B can facilitate and expedite diagnosis. With the enhanced ability to detect kidney injury options, potentially reducing the risk of progression to chronic kidney disease, veterinarians now have the chance to intervene with treatment options , potentially reducing the risk of progression to chronic kidney disease prior to the development of chronic kidney disease.

  A first-of-its-kind veterinary test to detect kidney injury. Learn more about the IDEXX Cystatin B Test.

Kidney Injury and Cystatin B

Cystatin B is a kidney biomarker that can be assessed to detect kidney injury even in the absence of changes in kidney function.^43,44 Until recently, diagnostic testing has been limited to markers related to kidney function such as SDMA and creatinine where some function must be lost before seeing a change in the associated laboratory value. However, when renal tubular epithelial cells are injured or destroyed, the intracellular protein cystatin B is released into the urine at the time of the injury. By testing cystatin B, veterinarians now have a way to detect kidney injury in at-risk cases prior to significant loss of function, offering the opportunity to intervene at an earlier phase of disease development.

Common Cases That Could Benefit From a Cystatin B Test

Knowing how a diagnostic test works or what that test is looking for is a critical and natural consideration for veterinarians when developing patient diagnostic plans. Feeling confident about when to choose or implement that test can be a little challenging, especially when it is new, and we don't have practice experience to draw from.

Here is a high-level look at common types of small animal veterinary cases that could benefit from cystatin B testing due to the patient's increased risk for kidney injury.

• Toxic substance ingestion: Ingestion of certain toxins, such as antifreeze, certain plants, medications (like nonsteroidal anti-inflammatory drugs), and cleaning agents can damage the kidneys.
• Previously diagnosed kidney disease or previous elevations in functional biomarkers: Patients with previously diagnosed kidney disease (who are now considered in the resolution phase) or those who've had previous elevations in kidney functional biomarkers could benefit from the incorporation of cystatin B testing in their monitoring plan.
• Chronic disease: Patients with chronic conditions such as diabetes and hyperthyroidism are at higher risk for kidney injury. The cystatin B test could be incorporated into the diagnostic plan to monitor for kidney damage along with assessing functional markers, allowing for earlier decision making as the patient progresses through the IRIS Stages.
• Infections: Patients found to have bacterial, viral, or fungal infections may have inflammation and damage to the kidneys.
• Hypertensive and hypotensive patients: Chronic or acute elevations in blood pressure can damage the delicate structures in the kidneys. Thus, patients who suffer from chronic blood pressure deviations, as well as patients who undergo acute situations, such as hypotensive events under anesthesia, could benefit from cystatin B testing.
• Trauma: Patients experiencing physical trauma such as blunt force injury or blood loss, or emergency cases with diminished systemic perfusion are at increased risk of secondary kidney injury.
• Urinary tract obstruction: Blockages of the urinary tract, caused by tumors or stones, can lead to kidney injury.
• Heartworm disease: Cardiovascular compromise, antigen antibody complex formation and/or the potential for emboli places these patients at increased risk of kidney injury.
• Cancers: Both primary kidney tumors and metastasis from other cancers can directly and indirectly damage kidney tissue.
• Sick patients: Inadequate nutritional intake or dehydration secondary to illness may also result in kidney injury.

Cystatin B as Part of a Comprehensive Kidney Assessment

Cystatin B is a new and exciting tool available to veterinarians that allows for the detection of kidney injury and offers the opportunity to make a difference in the lives of patients who are at risk for both kidney injury and future chronic kidney disease. However, a full view of kidney health includes assessing for changes in function along with injury. To provide the clearest window into the health of your patients' kidneys, a plan that includes tests for markers of function such as SDMA, creatinine, blood urea nitrogen, and urinalysis is ideal. By being informed of both injury status and functional status of the kidneys, veterinarians can develop data-driven treatment plans that give their patients the best chance at longer, healthier lives.

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