Chronic kidney disease Flashcards
chronic renal failure is the?
end result of chronic persistent renal disease
Define Acute kidney disease?
- Reversible disease if detected early enough
- there are enough surviving nephrons
- treatment is started quickly
- Prevention of acute kidney disease is better than any treatment
- Sudden onset means there is no time for compensatory mechanisms
Every nephron is what?
Every nephron is precious …..”every little helps” in our mission to save the kidneys!
Define Chronic kidney disease?
- Irreversible “end stage” kidney disease
- manageable not curable
- Gradual and progressive loss of nephrons
- Clinical signs may have been present for weeks-months-years
- polydipsia
- polyuria
- weight loss
- lethargy
- decrease in appetite
- Above all typical signs of renal disease
Are there any useful clinical features to differentiate between AKI and CKD?
*There are exceptions to every rule: PKD, lymphoma, FIP. Kidneys become large in these
PKD= polycystic kidney disease, FIP= feline infectious peritonitis
Are there any useful laboratory features to distinguish CKI and AKI?
*There are exceptions to every rule: an underlying disease predisposing to AKI could also be causing anaemia; a patient with AKI could have GI bleeding and become anaemic.
CKD dogs fed a renal diet and on ACE-I for hypertension might be more at risk of?
Becoming hyperkalaemic in late stage renal disease. Sometimes these dogs need to have a specially formulated diet to counteract this but often it is not of any clinical significance in terms of the “big picture” of the dog’s problems.
CKD is a?
Polyuric state
- urine output > 50 mls/kg /day (>2mls/kg/hr)
- Kidneys cannot concentrate urine
- Produce urine of a low USG
Normal water intake is between?
- dogs can be up to 60-90mls/kg/day
- cats probably up to 45 mls/kg/day
With regards to urine output AKI cases can be?
- oliguric (urine output <0.5mls/kg/hour) Reduced renal ouput the kidney cannot concentrate or produce urine
- anuric
- polyuric (less likely)
Look at this schematic for chronic kidney disease?
Why is it important to record weight at every vet visit?
One of the reasons for recording weight in patients at every trip to the vets is to help clarify if a patient has lost weight because owners often don’t know when weight loss is slowly progressive.
Discuss diagnosis of CKD with regards to blood tests?
Azotaemia
•>75% functional loss of nephrons
creatinine can be normal in
- early CKD
- cases with poor muscle mass
SDMA
- for early CKD?
- <25% nephrons lost
Discuss diagnosis of CKD with regards to Urinalysis?
- SG inappropriately dilute for the level of azotaemia*
- dog <1.030
- cat <1.035 (cats concentrate better even with CKD)
- urine concentrating ability is affected with >66% functional loss of nephrons
Discuss exception to the rule with USG?
*Exceptions to every rule:
Producing hyposthenuric urine (SG <1.008) requires functional tubules. Such a low SG is therefore unlikely to be due to intrinsic kidney disease
What does SDMA stand for?
symmetric dimethylarginine assay
How do cats differ to dogs?
Note that cats are better at maintaining urine concentrating ability than dogs and therefore can still have renal azotaemia at a relatively higher urine concentration (Urine SG 1.033-1.035) compared with dogs. Dogs with CKD are usually unable to concentrate urine to an SG >1.030. If the kidneys are working, azotaemic patients should have very concentrated urine because the body is trying to conserve water ie they are dehydrated.
What should you never do?
Never (ever!) interpret raised creatinine +/or urea without urinalysis for urine SG
When might pre renal azotaemia be a challenge to our diagnosis of CKD?
- a CKD patient who is dehydrated
- the azotaemia might seem worse due to dehydration
- IRIS staging is only appropriate in a stable patient
- an azotaemic cat with relatively concentrated urine (SG 1.030) and vague clinical signs
- a dog who is on furosemide with restricted access to water
To rule out any influence of pre renal azotaemia give fluid therapy and assess the response to treatment
•pre renal azotaemia resolves quickly with IVFT
Dogs on furosemide should never have what restricted?
have water restriction but sometimes this happens (despite what we say!) because owners think it’s an appropriate thing to do if they are struggling with a dog who is polyuric. In fact what will happen is the dog will continue to produce excessive urine volume due to the furosemide and can become dehydrated. Renal perfusion then reduces and they can become azotaemic. The combination of azotaemia and low urine SG could be misdiagnosed as intrinsic kidney disease if we fail to take in to account the medication the dog is on. As a clinical example: think about a geriatric dog in heart failure
Diagnostic imaging & CKD: is it worthwhile for small or normal kidneys?
Radiography:
- confirms renal size
- margination
- are there 2 kidneys?
- any 2ry problems
- dystrophic calcification
- loss of bone density
Ultrasound:
- normal?
- change in echogenicity?
- loss of corticomedullary border
Diagnostic imaging is often unhelpful if both kidneys are already small
Diagnostic imaging & CKD: is it worthwhile for Enlarged kidney(s)?
Radiography:
•confirms renal size
Ultrasound:
- normal?
- change in echogenicity?
- polycystic kidney disease
- FIP
- lymphoma
- perinephric pseudocyst
Can we palpate cats kidneys?
we should nearly always be able to palpate a cat’s kidneys unless they are really obese or the kidneys are especially small
Can we palpate dog kidneys?
We can palpate the kidneys in some but definitely not all dogs…it isn’t just you! Think about the body shape, where the kidneys are and then work out how likely it is you will feel them. If the kidneys are enlarged then that might be easier. Think about the need for diagnostic imaging to assess renal size and shape in dogs.
What are the indications fo Renal biopsy & CKD?
- Suspected neoplasia
- Familial nephropathy where results might have an impact on other animals. Biopsy may change situation for siblings or breed in general
- Non azotaemic protein losing nephropathy
- ie kidney disease not failure
Biopsying a small fibrotic “end stage” kidney will not contribute to management of the case but will contribute to risks and costs. Need to be confident it will change your treatment. Not relevant for CKD but maybe indicated for lymphoma.
What is the prognosis for CKD in cats?
- approx. 30-50% of cats >15 yrs old have CKD
- can have stable CKD for months to years
- can have CKD and die of another disease
What is the prognosis for CKD in dogs?
- approx. 10% of geriatric dogs have CKD
- progressive, linear, more rapid deterioration common in dogs than cats
- are more likely to die of CKD if they have CKD
What are the Markers associated with progression of CKD:
worsening azotaemia, anaemia, high blood pressure, proteinuria, soft
tissue mineralisation
The markers associated with progression of CKD signify consequences of CKD but also contribute to further deterioration
Think about something that might have destabilised the patient with CKD e.g?
GI upset, 2ry UTI, respiratory infection, stress of some kind, restricted access to water, a cat that goes off its food or has not been fed
What does the sick patient with CKD suffer from?
Discuss a stabilisation plan for CKD?
Fluid therapy to restore deficit, provide maintenance and cover any on-going losses
- crystalloid eg Hartmann’s
- addresses any pre renal component to azotaemia
- remember your patient is polyuric
- what impact does that have on ongoing losses?
Correct hypokalaemia if necessary (cats with renal failure pee more of it out)
- with iv fluids?
- oral?
Anti emetics: also help with nausea in cats
- NK-1 receptor antagonist (maropitant)
- metoclopramide CRI (less effective?)
Gastroprotectants:
- sucralfate
- H2 receptor antagonist
- ranitidine, cimetidine, famotidine
Target organs for damage secondary to systemic hypertension include the?
Eyes, kidneys (exacerbating an already bad situation) and central nervous system. The heart can also be adversely affected by hypertension but this is more of a theoretical list.
What do renal care diets diets also aim to do: is it just about phosphate restriction?
Is there a role for calcitriol in managing hyperparathyroidism?
Calcitriol is not a substitute for renal care diet or phosphate binders
Illustrate the exacerbating cycle of proteinuria?
Look at this IRIS staging chart?
It is likely that modification of IRIS staging will occur at some point as SDMA becomes more accepted as a marker for early renal disease. Keep referring to the website as a useful resource now and in the future!
* Early CKD may be detected by palpation of small or abnormal kidneys, PU/PD with no other cause found, proteinuria consistent with renal origin (ie you have ruled out other causes of proteinuria such as UTI).
IRIS staging: what is the current role of SDMA?
Discuss Functional reserve of the kidneys?
Compare functional reserve to IRIS staging?
Outline IRIS sub-staging: proteinuria?
Ideally based on 2 separate urine samples collected at least 2 weeks apart
Rule out post renal proteinuria ie UTI and lower urinary tract inflammation and/or haemorrhage before trying to interpret the UPCR
- Borderline proteinuric patients can be re-evaluated in 3-6 months
- You can consider pooled samples to check UPCR to avoid issues with day to day variability eg samples from 3 days all pooled together to run through the lab as one sample (reducing costs)
Discuss IRIS sub-staging: of arterial systolic blood pressure (Doppler)?
TOD= target organ damage
What are Abyssinian cats more at risk from?
The picture is an Abyssinian and these cats are more at risk of a relatively rare problem- amyloidosis.
Discuss Polycystic Kidney Disease (PKD) in cats?
- Persian & related breeds, exotic and British short hair
- Autosomal dominant inheritance
- Cysts often seen from 8 mths of age with ultrasound
- Azotaemia may not develop for years
- DNA test now available so may help with control through selective breeding
