PATHOLOGY - Chronic Kidney Disease Flashcards
What is chronic kidney disease (CKD)?
Chronic kidney disease (CKD) is a progressive, often irreversible loss of functional renal tissue
What is chronic kidney failure?
Chronic kidney failure is endstage chronic kidney disease where there is azotaemia and reduced urine concentrating function
What is stage I chronic kidney disease (CKD)?
Patient is not azotaemic
What is stage II chronic kidney disease (CKD)?
Patient is mildly azotaemic
What is stage III chronic kidney disease (CKD)?
Patient is moderately azotaemic
What is stage IV chronic kidney disease (CKD)?
Patient has severe azotaemia
Describe the pathophysiology of chronic kidney disease (CKD)
There will be a trigger for chronic kidney disease (CKD) which results in nephron damage. Prolonged injury and damage to the nephrons will result in the infiltration of inflammatory cells and profibrotic cytokines which will result in renal hypoxia and further damage. As the nephrons are damaged, the remaining functional nephrons will have to compensate and filter more blood. In the early stages of disease, the remaining nephrons will hypertrophy to increase their glomerular filtration rate and filter more blood, however, in the later stages of disease, these compensatory mechanisms will become overwhelmed resulting in clinical kidney disease. When there is less than 1/3 of functional nephrons remaining, this will result in impairment of urine concentration and where there is less than 1/4 of functional nephrons, the patient will develop azotaemia. As the disease and azotaemia progress, uraemia will develop
What is the most common cause of chronic kidney disease (CKD) in cats?
Chronic interstitial nephritis
What is the most common cause of chronic kidney disease (CKD) in dogs?
Glomerulonephritis
What are the potential consequences of chronic kidney disease (CKD)?
Azotaemia
Uraemia
PUPD
Hyperphosphataemia
Renal secondary hyperparathyroidism
Hypokalaemia
Anaemia
Systemic hypertension
Haemorrhage
Proteinuria
Metabolic acidosis
How does chronic kidney disease (CKD) cause hyperphosphataemia?
Phosphate is usually excreted via filtration through the glomeruli, however, when the glomerular filtration rate (GFR) is reduced, this will reduce the excretion of phosphate resulting in hyperphosphataemia
How does chronic kidney disease (CKD) cause renal secondary hyperparathyroidism?
Chronic kidney disease (CKD) causes a decreased glomerular filtration rate (GFR) which will result in hyperphosphataemia. Serum phosphate forms complexes with serum calcium resulting in decreased levels of calcium and hypocalcaemia. Furthermore, renal tissue damage results in decreased calcitriol release resulting in decreased dietary calcium absorption in the gastrointestinal tract and hypocalcaemia. In response to hypocalcaemia, the parathyroid gland will release parathyroid hormone which will increase gastrointestinal absorption of calcium and mobilise calcium in the bone. This can result in osteopenia, tooth loosening and pathological fractures. Furthermore, parathyroid hormone is throught to be a uraemic toxin and thus can exacerbate uraemia and cause further renal tubular damage
How does chronic kidney disease (CKD) cause hypokalaemia?
Decreased dietary intake due to inappetence
Increased loss due to vomiting and diarrhoea
Decreased renal reapsorption of potassium
Renal tubular acidosis
How can hypokalaemia present clinically?
Neuromuscular weakness
Arrhythmias
Metabolic acidosis
PUPD
What is a key signs of neuromuscular weakness secondary to hypokalaemia?
Ventroflexion of the neck
How does hypokalaemia promote PUPD?
Hypokalaemia promotes PUPD as adequate serum potassium is required for effective function of antidiuretic hormone (ADH) which triggers reabsorption of water at the collecting duct
How does chronic kidney disease (CKD) cause anaemia?
Chronic kidney disease results in decreased erythropoietin production which can result in anaemia which can promote further kidney disease due to renal hypoxia
Which anaemia results due to chronic kidney disease (CKD)?
Non-regenerative, normocytic normochromic anaemia
How does chronic kidney disease (CKD) cause hypertension?
Chronic kidney disease (CKD) can cause hypertension as chronic kidney disease (CKD) will result in impaired sodium excretion resulting in hypernatraemia. Furtheremore, the renin-aldosterone-angiotensin system (RAAS) which will trigger hypertension
What are the risks of systemic hypertension secondary to chronic kidney disease (CKD)?
Systemic hypertension can cause target organ damage to the kidneys, brain, eyes and cardiovascular system
How can chronic kidney disease (CKD) cause haemorrhage?
Chronic kidney disease can cause ocular haemorrhage secondary to systemic hypertension as well as gastrointestinal haemorrhage secondary to ulceration due to gastrointestinal irritation due to uraemic toxins
However this is rare
Hoq can chronic kidney disease (CKD) cause metabolic acidosis?
Chronic kidney disease (CKD) results in decreased excretion of H+ in the urine resulting in metabolic acidosis. Furthermore, chronic kidney disease causes vomiting and diarrhoea which also results in bicarbonate loss and metabolic acidosis
What are the two main causes of disease progression in chronic kidney disease (CKD)?
- Persistence of initial trigger of chronic kidney disease (CKD)
- Secondary processes which perpetuate the chronic kidney disease (CKD)
Which secondary processes perpetuate chronic kidney disease (CKD)?
Hyperphosphataemia
Renal secondary hyperparathyroidism
Anaemia
Systemic hypertension
Proteinuria
Metabolic acidosis
Renal inflammation
Renal fibrosis
How do you approach the diagnosis of chronic kidney disease (CKD)?
- Assess history and clinical signs
- Clinical examination
- Haematology and biochemistry
- Urinalysis
- Diagnostic imaging
- Blood pressure
What are the potential clinical signs of chronic kidney disease (CKD)?
PUPD
Weight loss
Lethargy
Anorexia
Dehydration
Vomiting/nausea
Haematuria
Abdominal distension
Subcutaneous oedema
Ascites
Acute blindness
Pathological fractures/tooth loosening
Small kidneys on palpation
Clinical signs of anaemia
Pain
What would you typically find on haematology in a patient with chronic kidney disease (CKD)?
Non-regenerative, normocytic, normochromic anaemia
Neutrophilia (if secondary infection)
When would you see a neutrophilia in a patient with chronic kidney disease (CKD)?
You would see a neutrophilia in a patient with chronic kidney disease (CKD) if they had a concurrent renal infection
What would you typically find on biochemistry in a patient with chronic kidney disease (CKD)?
Azotaemia
Hyperphosphataemia
Hypokalaemia
Hyper- or hypocalcaemia
Metabolic acidosis
What would you typically see on urinalysis in a patient with chronic kidney disease (CKD)?
Low urine specific gravity (USG)
Urine sedimentation
Proteinuria
Why is it important to send urine samples for culture and sensitivity in patient with chronic kidney disease (CKD)?
It is important to send urine samples for culture and sensitivity in patients with chronic kidney disease (CKD) as they are more susceptible to concurrent renal infections and these infections can propagate disease
How can chronic kidney disease (CKD) appear on radiography?
Small kidneys
Renal mineralisation
Why is radiography particularly useful in cats with chronic kidney disease (CKD)?
Cats commonly get chronic kidney disease (CKD) secondary to ureteroliths which are more easily detected on radiography
When would it be appropriate to do a renal fine needle aspirate (FNA)?
It would be appropriate to do a renal fine needle aspirate (FNA) if you suspect renal lymphoma
What are the aims of treatment of chronic kidney disease (CKD)?
Treat underlying cause if possible
Improve clinical signs/quality of life
Slow disease progression
What are the potential underlying causes of chronic kidney disease (CKD)?
Hypercalcaemia
Renal lymphoma
Nephrotoxic drugs
Glomerular disease
Pyelonephritis
Infectious disease
Ureteroliths
Systemic hypertension
Which clinical signs should you manage in patients with chronic kidney disease (CKD)?
Dehydration
Vomiting/nausea
Systemic hypertension
Anorexia
Hypokaelamia
Anaemia
How do manage dehydration secondary to chronic kidney disease (CKD) in the short term?
Intravenous fluid therapy
How do manage dehydration secondary to chronic kidney disease (CKD) in the long term?
Increase oral fluid intake
Subcutaneous fluids
Feeding tube
Manage ongoing losses (i.e. vomiting)
What can be done to increase oral fluid intake in patients with chronic kidney disease (CKD)?
Add water to feed
Wet food
Continuous access to fresh water
What are the causes of vomiting in patients with chronic kidney disease (CKD)?
Stimulation of the chemoreceptor trigger zone by uraemic toxins
Uraemic gastritis
Hypergastrinaemia
What can be done to manage vomiting in patients with chronic kidney disease (CKD)?
Antiemetics
Gastroprotectants
Which gastroprotectants should you use when managing vomiting secondary to chronic kidney disease (CKD)?
H2 blockers
Proton pump inhibitors
Sucralfate
How do you manage systemic hypertension in dogs with chronic kidney disease (CKD)?
ACE inhibitors
How do you manage systemic hypertension in cats with chronic kidney disease (CKD)?
ACE inhibitors
Amlodipine
Angiotensin receptor blockers
How can you manage anorexia due to chronic kidney disease (CKD)?
Hand feeding
Appetite stimulants
Feeding tube
Give an example of an appetite stimulant
Mirtazapine
How can you manage hypokalaemia due to chronic kidney disease in the short term?
Potassium supplementation via intravenous fluid therapy
How can you manage hypokalaemia due to chronic kidney disease (CKD) in the long term?
Renal diets (as they contain potassium supplementation)
Oral potassium supplements
How can you manage anaemia secondary to chronic kidney disease (CKD)?
Erythropoietin therapy using recombinant human erythropoietin (rHuEPO) or darbepoietin-α
When is erythropoeitin therapy indicated?
Erythropoeitin therapy is indicated in patients with a PCV of less than 20% and presenting with clinical signs of anaemia
What can be done to slow disease progression for chronic kidney disease (CKD)?
Manage hyperphosphataemia and renal secondary hyperparathyroidism
Omega-3 supplementation
Manage systemic hypertension
Manage proteinuria
How do you manage hyperphosphataemia?
Reduce dietary phosphate (renal diet)
Intestinal phosphate binders
How should you administer intestinal phosphate binders?
Mix intestinal phosphate binders with every meal
Which is omega-3 supplementation used to slow chronic kidney disease (CKD) progression?
Omega-3 has a renal protective function (can be found in renal diets)
What are the components of prescription renal diets?
High energy
High quality but reduced protein
Phosphate restricted
Sodium restricted
Potassium supplemented
Omega-3 supplemented
Anti-oxidant supplementation
Increased soluble fibre
Neutral effect on acid base balance
Increased B vitamins
Try to use the wet diet to increase oral fluids
When should you not convert chronic kidney disease (CKD) patients to a renal diet?
Do not convert patients to a renal diet if they are in a uraemic crisis or if they are hospitalised as this can create a bad association with the feed and reduce the chance of the patient wanting to eat it
How should you introduce a renal diet to a chronic kidney disease (CKD) patient?
Renal diets are for long term management of chronic kidney disease (CKD) so introduce the diet slowly over 3 to 4 weeks. This diet is not very palatable to animals due to the reduced protein, so it is important to introduce it slowly and educate owners about the benefits of this diet so they don’t give up
What can be used to manage proteinuria in patients with chronic kidney disease (CKD)?
Renal diets
ACE inhibitors
Angiotensin receptor blockers
How do renal diets help to manage proteinuria?
Renal diets are restricted in protein and contain omega-3 which is a renal protectant
How do ACE inhibitors manage proteinuria?
ACE inhibitors inhibit angiotensin converting enzyme (ACE) which will prevent conversion of angiotensin I to angiotensin II, which is a potent vasoconstrictor. This will reduce glomerular hypertension and reduce the secretion of serum proteins into the urine
Give two examples of ACE inhibitors
Benazepril
Enalapril
How do angiotensin receptor blockers manage proteinuria in patients with chronic kidney disease (CKD)?
Angiotensin receptor blockers inhibit the binding of angiotensin II to their AT1 receptors, reducing glomerular hypertension and consequently reducing the secretion of serum proteins into the urine
Which species are angiotensin receptor blockers licensed in?
Cats
Give an example of an angiotensin receptor blocker?
Telmisartan
What are your aims in long term monitoring of chronic kidney disease (CKD)?
Assess for disease progress
Monitor for complications
Assess response to management of previously diagnosed complications
Client education and support
What is acute-on-chronic kidney disease?
Acute-on-chronic kidney disease is the acute deterioration of patients with chronic kidney disease as a consequence of a new onset kidney injury (AKI)
Sudden deterioration is not typical of CKD so always do further investigations
How do you manage acute-on-chronic kidney disease?
Manage acute-on-chronic kidney disease with intravenous fluid therapy
What is the prognosis for chronic kidney disease (CKD)?
The prognosis of chronic kidney disease is dependent on the stage of the disease, development of secondary conditions and quality of management
