Chronic Kidney Disease (Rolph) Flashcards
What is chronic kidney disease and who does it affect?
Common cause of illness and mortality in feline patients
- Approx. 10% of cats older than 10 years
- 30% of cats older than 15 years
- Less common in dogs but stil affects 0.5-1.5% of dogs
How is chronic kidney diseases diagnosed?
Based on anything that suggests kidney failure has been present for an extended time (typically more than 2 mos.)
- History
- Physical exam
- Lab findings
What are the clinical signs of chronic kidney disease?
- PU/PD (most common sign)
- Anorexia
- Hypersalivation (due to oral ulceration, tongue tip necrosis)
- Constipation (2o to chronic dehydration, vomiting)
What might the vomiting or chronic dehydration cause other than constipation?
- Uremic gastritis
- Poor body condition
- Poor hair coat
- Small kidneys
What’s seen on clinical examination with chronic kidney disease?
- Dehydrated
- Poor body condition/underweight
- Pale mucus membranes
- Small kidneys
- Hypertensive retinopathies
- (Loose teeth, deformed maxilla/mandible/fractures)
What are the consequences of renal dysfunction?
- Failure of excretion of nitrogenous wastes → uremia → ulceration (oral and Gi) and shortened RBC lifespan
- Failure or urine concentration → PU/PD → predisposes to UTIs and volume depletion → constipation
- Failure to syntheized calcitriol (VitD3) → renal 2o hyperparathyroidism → decreased bone density
- Failure to synthesize erythropoeitin → anemia
- Failure to catabolize peptide hormones (e.g. gastrin) → uremic gastritis
- Activation of RAAS → systemic hypertension
What should be looked at on bloodwork assessing chronic kidney disease?
- Urea
- Creatinine
- I-phosphate
- Calcium
- Potassium
- Albumin
- PTH
- SDMA in early cases and possible if concerns reclassification
- HCT
- WBC
What’s assessed with urine analysis in chronic kidney disease?
- Specific gravity
- Dipstick
- Sediment examination
- Protein:creatinine ratio
- Culture and sensitivity
What further diagnostics should be done with chronic kidney disease?
- Blood pressure measurement
- Retinal examination
- Abdominal ultrasound
- Blood gas (pH)
What’s the etiology of chronic kidney disease?
In most cases, cause of CKF not identified
What does histopathology demonstrate with chronic kidney disease?
Chronic interstitial nephritis
What is chronic interstitial nephritis and what’s it seen in?
- Idiopathic intrinsic degenerative disease
- Occurs mainly in older animals
What is chronic interstital nephritis thought to be the result of?
- Previous toxic insults
- Immune-mediated processes
- Result of chronic inflammatory disease
What diseases can occur as a result of na identificable ause regarding chronic kidney disease?
- Congenital deformities (i.e. renal dysplasia, PKD)
- Infarctions
- Infiltration w/ neoplastic cells (i.e. lymphoma)
- Obstructive disease (‘Big kidney, little kidney’)
- Infections (i.e. leptospirosis, pyelonephritis)
- Secondary to hypercalcemia
What are the IRIS stages of chronic kidney disease and their respective blood creatinine levels for dogs and cats?
- At risk
- Dogs: < 125 µmol/L or < 1.4 mg/dl
- Cats: < 140 µmol/L < 1.6 mg/dl
- 1
- Dogs: < 125 µmol/L or < 1.4 mg/dl
- Cats: < 140 µmol/L or < 1.6 mg/dl
- 2
- Dogs: 125-180 µmol/L or 1.4-2.0 mg/dl
- Cats: 140-250 µmol/L or 1.6-2.8 mg/dl
- 3
- Dogs: 181-440 µmol/L or 2.1-5.0 mg/dl
- Cats: 251-440 µmol/L or 2.9-5.0 mg/dl
- 4
- Dogs: > 440 µmol/L or > 5.0 mg/dl
- Cats: > 440 µmol/L or > 5.0 mg/dl
What’s important about the IRIS staging?
Gives more information on treatments and prognoses
What are the caveats regarding IRIS staging?
- Can’t stage/evaluate when dehydrated or sick
- Stage when the animal/patient is stable
What is the basis for an ‘at risk’ IRIS staging?
- History suggests animal is at an increased risk of developing CKS in future due to multiple factors, i.e.:
- Exposure to nephrotoxic drugs
- Breed
- High prevalence of infectious disease in the area
- Old age
What’s the basis for a ‘stage 1’ IRIS staging?
- Nonazotemic
- Some other renal abnormality present, i.e.
- Inadequate urinary concentrating ability w/o identifiable renal cause
- Abnormal renal palpation or renal imaging findings
- Proteinuria of renal origin
- Abnormal renal biopsy results
- Increasing blood creatinine concentrations in samples collected serially
What’s the basis for a ‘stage 2’ IRIS staging?
- Mild renal azotemia
- Clinical signs usually mild or absent
With an IRIS ‘stage 2’ staging, what’s important about the mild renal azotemia present?
Lower end of range lies w/n reference ranges for many labs, but insensitivity of creatinine concentration as a screening test means that animals w/ creatinine values close to the upper referecne limit often have excretory failure
What’s the basis for a ‘stage 3’ IRIS staging?
- Moderate renal azotemia
- Many extrarenal clinical signs may be present
What’s the basis of a ‘stage 4’ IRIS staging?
Increasing risk of systemic clinical signs and uremic crises
What is the role of angiotensin II in chronic renal disease?
What are the pathological processes leading to proteinuria?
How are dogs and cats classified in each of the IRIS stages?
According to urine protein concentration
What are the subclassifications for proteinuria of renal origin and their UP/C values?
- Non-proteinuric (dogs <0.2, cats: <0.2)
- Borderline proteinuric (dogs: 0.2-0.5, cats: 0.2-0.4)
- Proteinuric (dogs: > 0.5, cats: >0.4)
What is the effect of proteinuria on survival?
Study w/ hypertensive cats
- UP/C > 0.4 poorer prognosis vs. UP/C < 0.4
- UP/C < 0.2 decreased mortality vs. UP/C > 0.2
What’s important about the urine protein creatinine ratio being a prognostic indicator and how can it be treated?
UP/C, irrespective of if increased protein in urine because of hypertension or CKD, is a negative prognostic indicator
- Can treat w/ drugs
What effect does blood pressure have on the glomerulus?
If blood pressure increased, the glomerulus and kidney can be damaged and cause further problems
What percent of cardiac output do the kidneys receive?
25%
What’s the purpose of high, constant blood flow through the kidney?
- Allows for excretion and homeostasis
- High blood flow needed for metabolic requirements and to maintain GFR
What’s the percentage of oxygen consumption by the kidneys?
8%
What finding in regards to blood pressure is associated with CKD and which occurs first?
CKD associated w/ elevated BP (RAAS activation)
- In many cases, unclear which occurs first
What drugs can help with the damage inflicted on the kidneys by hypertension?
- Have drugs that can inhibit RAAS
- Decrease effects of hypertension on kidneys and decrease mechanism that damage kidneys
What are the mechanisms of renal damage in hypertension?
- Glomerular hypertension
- Hyperfiltration
- Glomerular barrier dysucntion
- Proteinuria
- Mesangial cell hyperplasia
- Intrarenal inflammatory processes
- Endothelial dysfunction
- VSMC proliferation
