Diagnosing the Spectrum of Kidney Injury in Pets
Acute kidney injury accounts for approximately one-third of renal cases, but until recently, early detection and diagnosis have proved difficult.6 We now know that when this occurs and renal tubular epithelial cells are injured or destroyed, they release an intracellular protein called cystatin B into the urine. Cystatin B has been identified as a biomarker for kidney injury and one we can measure for detection of injury in our patients.24
As we dig deeper into kidney injury, it's important to understand that there's a large spectrum of kidney injury ranging from subclinical to severe. We can further categorize these injuries into four types of insults ranging from a single, mild, subclinical event to the most severe form that causes the progression of chronic kidney disease.42
Single, Mild, Subclinical Event
Transient and isolated subclinical events in a patient's life can cause a mild kidney injury. Unfortunately, as the description implies, these are often fleeting, or worse, unnoticed, and therefore may not immediately trigger the need for diagnostics. Mild events like temporary dehydration, fever, or inadequate nutritional intake may not permanently affect function. Still, as clinicians, we need the objective data of diagnostics to help rule out the need for further workup and help guide prognosis and ongoing treatment plans.
Ongoing Mild Injury
Other pets may have ongoing mild kidney injury that remains undiagnosed. For example, some patients may have undetected or unmanaged hypertension, either as a primary entity or secondary to a chronic disease like diabetes mellitus or hyperadrenocorticism. Cats and dogs can also experience mild kidney injury that may eventually affect function through the use of medications like non-steroidal anti-inflammatories (NSAIDs), aminoglycosides, and chemotherapeutic agents. Still, another group of patients at risk of ongoing mild injury is those with infectious diseases caused by viral, bacterial, and fungal organisms, as well as vector-borne diseases like ehrlichiosis and heartworm disease. While these conditions may not immediately cause harm, they may eventually decrease kidney function. Early detection of these causes of mild injury can help identify possible therapies and potentially lead to resolution for the kidneys and other major organ systems.
Acute Kidney Injury
A common example of acute kidney injury is toxin exposure. Unfortunately, veterinarians frequently see patients who have had exposure to or ingested ethylene glycol, grapes or raisins, vitamin D, cleaning agents, and lilies, and, up until recently, have only been able to detect active disease at more advanced stages. While these acute kidney injuries can be severe and affect function, some may resolve if treated. Early detection of renal tubular epithelial cell injury with or without changes in functional markers using the cystatin B test offers the opportunity to intervene and potentially change the outcome for patients who have experienced kidney injury.43,44
Progressive Chronic Kidney Disease
The last group of patients already have impaired kidney function, as they have been previously diagnosed with chronic kidney disease. However, when these patients develop an undetected infection, experience fluctuations in blood pressure resulting in hypo- or hypertension, or are exposed to medication that can harm the kidneys, kidney injury can occur and exacerbate this impairment through a progression of the disease. While patients with chronic kidney disease have changes to function that cannot be reversed, early identification and treatment of concurrent kidney injury can help slow down progression. This is extremely important for not only quantity but quality of the patient's life.46
Managing kidney health in pets requires frequent monitoring, diagnostics, and when possible, early intervention to slow down progression. Early detection and intervention are key tenets in managing these pets' kidney health. Adding diagnostics for the detection of kidney injury to the standard blood and urine testing gives veterinarians the opportunity for early detection and better treatment outcomes. With routine monitoring, veterinarians can take proactive steps to address patient kidney status changes.
References: https://www.thevetiverse.com/en/latest/sdma-references/
