Understanding Kidney Disease Terminology
From a practical standpoint, the terms chronic kidney disease (CKD), chronic renal failure (CRF), renal insufficiency, chronic kidney failure, and kidney insufficiency all refer to the same condition. For simplicity in this article, the term chronic kidney disease (CKD) will be used to reflect all these terms or conditions.
What is Chronic Kidney Disease (CKD) In Cats?
CKD occurs when the kidneys can no longer function adequately, leading to the need for additional support to maintain normal bodily functions. The disease progresses through various stages, each requiring different levels of care and treatment.
Kidney Functions and Insufficiency
Kidney function goes far beyond urine production. Kidneys separate necessary chemicals from those to be excreted in urine. Here's what kidneys do and what they fail to do in renal insufficiency:
Hydration Management
Kidneys regulate body hydration by conserving water during dehydration and excreting excess water when overhydrated. Pets with insufficient kidney function can't produce concentrated urine and need to drink extra water to process waste. Excessive water consumption is an early warning sign and should be investigated.
Urine Specific Gravity
Analyzing urine's specific gravity measures its concentration. Water's specific gravity is 1.000. Dilute urine has less than 1.020 (often less than 1.010), while concentrated urine exceeds 1.030 or 1.040. Failing kidneys can't produce concentrated urine, leading to excessive drinking to eliminate toxins.
Waste Management
Kidneys remove metabolic wastes. If circulation through the kidneys is inadequate or there are insufficient functioning nephrons, toxins build up, leading to azotemia. If toxins reach a level that makes the patient feel sick, it is called uremia. Key markers for uremia include creatinine, SDMA, and BUN levels.
Calcium and Phosphorus Regulation
Kidneys regulate the balance between calcium and phosphorus. Insufficient kidney function causes phosphorus levels to rise, requiring dietary and medication management to maintain balance and prevent crystal formation in tissues.
Sodium/Potassium Balance
Kidneys control electrolyte balance, conserving potassium. Insufficient kidneys lose this ability, leading to low potassium levels and weakness. Potassium supplements are often necessary.
Blood Pressure Regulation
Kidneys help regulate blood pressure. Damaged sensors can cause hypertension, further damaging the kidneys. Blood pressure monitoring is crucial in chronic kidney disease patients.
Protein Conservation
There are many essential proteins in the bloodstream, and it is vital to ensure they are not lost in the urine. Nephrons' filtration systems retain necessary proteins while removing wastes. Damage to this system leads to severe kidney failure. Screening includes a urine protein
ratio to assess this condition.
Red Blood Cell Production
Kidneys produce erythropoietin, a hormone stimulating red blood cell production. Lack of this hormone causes anemia, sometimes requiring transfusions. Erythropoietin injections can treat this but have potential pitfalls.
pH Balance and Metabolic Efficiency
Kidneys regulate pH balance. If they fail, fluid therapy may be needed to maintain the balance necessary for metabolic processes.
Managing Chronic Kidney Disease in Cats and Dogs
Treatment Goals
With chronic kidney disease, one or more kidney functions may falter. The goal through early detection and intervention is to slow disease progression. Advanced stages focus on symptom control and maintaining quality of life. Early screening is crucial for easier management.
Chronic Kidney Disease (CKD) Stages in Cats and Dogs
Chronic kidney disease (CKD) in cats is staged based on creatinine and SDMA levels, according to the The International Renal Interest Society (IRIS). Here's a breakdown of each stage and its key characteristics:
Stage I: Early Detection
Characteristics: Known kidney disease based on abnormal ultrasound or slightly elevated SDMA.
Monitoring: Quarterly checks for blood pressure, urinary protein levels, and urinary tract infections.
Stage II: Early Symptoms
Recommendations: Diet change to a renal diet
Monitoring: Focus on phosphorus (below 4.6 mg/dl) and potassium levels. Medications may be needed if diet is insufficient.
Stage III: Noticeable Symptoms
Symtoms: Reduced appetite, occasional nausea.
Monitoring: Red blood cell count, blood pH, and possibly starting calcitriol (active vitamin D).
Stage IV: Advanced Symptoms
Symptoms: Noticeable discomfort and reduced appetite.
Monitoring: Phosphorus goals (6.0 mg/dl) and fluid support, including subcutaneous fluids or IV fluids if needed.
Advanced Cases: Severe Kidney Dysfunction
Presentation: Creatinine levels above 5.0 mg/dl, potentially reaching 10 mg/dl
Treatment: Aggressive stabilization and gradual transition to a renal support diet
Table: Creatinine Values for Each IRIS Stage listed in US, International, and SDMA Units
Is Your Cat Just Diagnosed with Chronic Kidney Disease? We Can Help!
If your beloved fur baby is diagnosed with chronic kidney disease, or you suspect such condiction may be present, Dr. Terry White at EverPal can give expert guidance, available after regular clinic hours. We can help provide the care your fur baby needs when you need most.
Schedule a same-day virtual visit with Dr. Terry White at EverPal.
Consultations are currently available only for residents and pets living in California. Diagnostic testing available for resdients in San Francisco, Daly City, Oakland, and Berkeley, California.
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