Chronic kidney disease Flashcards
Define chronic kidney disease
Structural or functional abnormalities of one or both kidneys that have been present for 3 months or longer
Describe the main features of damage in CKD
- Compensatory/adaptive changes have already occurred
- An irreversible, slowly progressive disease
- After 3months have passed, you should not expect improvement in renal function
- There is a permanent reduction in the number of functioning nephrons and reduced GFR
Define azotaemia
Azotaemia is an abnormal concentration of urea, creatinine and other nitrogenous compounds in the blood.
- Doesn’t mean abnormal renal function- there can be other causes
Define uraemia
The clinical syndrome that results from loss of kidney function, involving multiple metabolic derangements
List the congenital causes of CKD
Renal dysplasia - Dogs
Polycystic kidney disease - Persian
Amyloidosis
Fanconi-like syndrome
List some acquired causes of CKD
Idiopathic tubulointerstitial nephritis
Glomerular disease
Amyloidosis
Sequel to AKI
Lower urinary tract obstruction
Pyelonephritis
Hypercalcaemia
Renal neoplasia
Nephrotoxic drugs
Hypokalaemia in cats (controversial)
Hypertension (debated)
What happens in CKD once the active kidney disease stops?
Continues to progress
Why does CKD continue to progress?
- Intraglomerular hypertension / ↑SNGFR (Increased single nephron GFR)
- Systemic hypertension
- Proteinuria
- Precipitation of calcium phosphate in renal tubules - initiates inflammation, fibrosis and atrophy.
Describe an increase in single nephron GRF
A compensatory event aimed at maximising total GFR when the number of nephrons is reduced
Describe the 4 stages of IRIS CKD
1 = primary renal injury
2 = mild azotaemia, maladaptation’s
3 = uraemia, systemic complications
4 = end stage renal failure
GRF decreases over these 4 stages of CKD
List the clinical signs of CKD
Weight loss
Poor appetite
Dullness, lethargy, sleeping more
PUPD
Dehydration
Vomiting
Constipation
Poor hair coat
Neurological signs
Signs related to hypertension
Oedema/ascites in severe protein losing CKD
CKD is primary staged using?
Plasma creatine concentration
CKD is substaged using?
Proteinuria
Blood pressure - risk of organ damage
How is CKD stages from 1-4 using plasma creatine conc?
1 = some other renal abnormality present e.g. inadequate concentrating ability
2 = clinical signs usually mild (e.g. PUPD) or absent
3 = extra-renal signs present
4 = requires intensive treatment
When should creatine be measured to stage CKD?
Ideally two or more stable creatinine concentrations are used, obtained over days or weeks, when the pet is fasted and well hydrated
Describe the steps in the diagnostic approach to CKD
Determine diagnosis and stage
Identify any ongoing active renal diseases
Identify any complications
Identify concurrent conditions
CKD is not a single disease- all patients are individuals!
What do the levels of urea correlate with?
Clinical signs
What do the levels of creatinine correlate with?
GFR
Muscle mass
Describe the haematology seen in CKD
- Normocytic normochromic non-regenerative anaemia can occur
- Possible decreased albumin in protein losing enteropathy
- Calcium levels vary
Why would you want to assess potassium levels in CKD patients?
Frequently low in cats with CKD
Increased in endstage CKD
Why would you want to assess phosphorus levels in CKD patients?
Indicates secondary hyperparathyroidism and metastatic calcification
Linked to increased mortality and progression of CKD
Describe urinalysis for CKD
May be normal if patient is hydrated
Is definitely abnormal in dehydration
Dipstick – check proteinuria
Sediment - WBC, RBC, casts, crystals
What are the principles of treatment for CKD?
- CKD is irreversible and usually progressive
- There is no cure
- Aim to provide good quality of life, reduce severity of c/s, minimise progression
How is a uraemic crisis treated?
- IVFT: Hartmann’s or 0.9% NaCl
- Supply ongoing maintenance requirements
- Monitor electrolytes and azotaemia
- Reduce IVFT as animal starts eating and drinking
- Don’t “flush” the kidneys!!
When is an animal classified as stage 1 CKD?
For an animal to be classified in Stage I, some other abnormality must be detected to create the suspicion that a disease is present in kidney tissue
List the abnormalities which may indicate stage 1 CKD?
- Inadequate urinary concentrating ability in the absence of an identifiable extra-renal cause,,
- Detection of renal proteinuria
- Abnormal size or shape of the kidneys on palpation, confirmed by diagnostic imaging
- Abnormal kidney biopsy findings
- Increasing creatinine concentrations (even if they remaining within the laboratory reference range) on serial sampling
What is the immediate action needed in stage 1 CKD?
- Stop all potentially nephrotoxic drugs.
- Identify and eliminate any on-going specific diseases if present - Often none can be identified
- Measure blood pressure and UPCR.
What are the 3 main steps to managing stage 1 CKD?
- Control dehydration
- Control hypertension (Goal is to reduce SBP to < 160 mmHg)
- Reduce proteinuria
How is dehydration controlled?
Feed a wet diet
Supply drinking fountains/dripping taps
Give cats a large bowl and fill it right up
Can try chicken/fish flavoured water
How is hypertension controlled?
ACEi
Telmisartan = Angiotensin receptor blocker
Amlodipine
How can proteinuria be reduced?
If proteinuria >0.5, start ACE inhibitor (correct dehydration before using ACE inhibitor) and a renal diet
- RAAS inhibition plus dietary protein reduction
- Antiplatelet drugs (low-dose aspirin, or clopidogrel)
- NO ACE INHIBITOR IN DEHYDRATED OR HYPOVALEMIC PATIENT
How is stage 2 CKD managed?
Same as Stage 1 plus the following:
- Start a renal diet
- Supplement potassium if needed
- Control phosphate to <1.5 mmol/l (diet, +/- phosphate binders to effect)
Why are renal diets beneficial?
- Protein restriction
- Phosphate restriction
- Ω-3 fatty acids
- Fibre
- ↓ sodium
- Water soluble vitamins
Why do you want to restrict protein in patients with CKD?
Ameliorates clinical signs
Reduced risk of uraemic crisis
Reduces proteinuria
Reduces PUPD
Reduces acid load
Which stages of patients will benefit from renal diets?
- Dogs in stage III and IV CKD
- Cats in stage II, III and IV CKD
- Dogs in stage II CKD when phosphate >1.5 mmol/L
- All dogs with proteinuric CKD
- Reduces c/s and prolongs life!
How can you help increase acceptance of a renal diet?
Educate the owner
Implement early
Introduce slowly
Don’t introduce them during times of stress
Consider temperature, texture…
Add flavour enhancers
Try another brand
How can you control the levels of serum phosphate in patients with CKD?
Reduce protein intake first (use a renal diet!)
Add phosphate binder if diet alone isn’t enough
How can you avoid hypokalaemia in patients treated for CKD?
Supplement IVFT with KCl
Oral supplements
- Potassium gluconate
- Potassium citrate
You’re treating a cat with CKD for a uraemic crisis. What food is best to offer the cat in hospital?
Any standard diet
Not a renal diet – this is for long term use, don’t want to cause food aversion by feeding in the hospital
How is stage 3 of CKD managed?
Same as stage 2 plus:
- Control vomiting/nausea/poor appetite
- Manage anaemia
How is vomiting/nausea/poor appetite controlled?
- Antiemetics
- Appetite stimulants (Mirtazapine, Capromorelin)
- Reduce gastric acid secretion
- Sucralfate
- Consider a feeding tube
How is anaemia managed in stage 3 CKD?
- Avoid excessive blood sampling
- Minimise GI blood loss (omeprazole/H2 antagonists/sucralfate)
- Treat iron deficiency (oral ferrous sulphate)
- Transfusions
- EPO replacement
What are the considerations/side effects of using EPO replacements?
Supplement iron if you give EPO
Side effects of EPO treatment: seizures, hypertension, local reactions, antibodies
How is stage 4 CKD managed?
Same as stage 3 plus:
- Control phosphate to <1.9 mmol/l (higher levels more tolerated than stage 3)
- Intensify efforts to provide nutrition
- More likely to require extra fluids (SC or via tube)
- Consider euthanasia
List the 4 steps involved in minimising progression of CKD
- Use a renal diet
- Control phosphate
- Control proteinuria
- Control blood pressure
Describe giving a prognosis for CKD
Unpredictable time course of the disease.
Hard to give a Px- depends on rate of progression and animal’s ability to tolerate azotaemia.
Diet seems to be most important
Proteinuria = Risk factor for uraemia and death
You’re monitoring a cat with CKD. What are your top 3 priorities to measure are ?
Creatinine
Phosphate
Potassium
Which intervention is CONTRAINDICATED when managing a uraemic crisis?
ACE inhibitors
