Chronic Kidney Disease Flashcards
What is the definition of chronic kidney disease (CKD)?
a reduction in kidney function or structural damage (or both)
that is present for more than 3 months
and has associated health implications
What test results would lead to a diagnosis of CKD?
people with a persistently reduced renal function - shown by an eGFR < 60 ml/min/1.73m2
and/or the presence of markers indicating structural kidney damage
What are the potential markers of kidney damage that might be identified?
- proteinuria
- urine sediment abnormalities (e.g. haematuria)
- electrolyte abnormalities (due to tubular disorders)
- abnormalities detected by histology
- structural abnormalities detected by imaging
- history of kidney transplantation
How is proteinuria detected?
there is a urinary albumin:creatinine ratio (ACR) > 3mg/mmol
What is significant about the diagnosis of CKD in most patients?
it is often asymptomatic and is picked up through routine investigations
How common is CKD?
9 - 13% of the adult population worldwide has CKD
prevalence related to aging population and increase in diabetes + HTN
Why is it important to try and recognise CKD in the early asymptomatic stages?
- it is often unrecognised until the most advanced stages
- it is mostly irreversible and progressive in nature
- detecting CKD in the early stages prevents it from advancing
What are the most significant implications of CKD on the patient?
- there is a high risk of complications + reduction in life expectancy
- it impacts the management and investigations of other conditions
- renal replacement is expensive + resource heavy
What is the most common and second most common RF & cause of CKD?
diabetes is the most common cause of CKD - 1/3 of diabetics will develop it
HTN is the second most common cause
HTN is also a consequence of CKD
What are other causes of CKD?
- glomerulonephritis
- systemic disease (e.g. SLE, amyloid, myeloma, vasculitis)
- renal artery stenosis
- heart failure
- hereditary (e.g. polycystic kidney disease)
- urinary tract obstruction (e.g. prostatic disease)
- chronic pyelonephritis / vesicoureteric reflux
- nephrotoxic drugs
What is the most readily available nephrotoxic drug?
NSAIDs
patients use these independently without knowing about the damage
What are some other common nephrotoxic drugs?
- lithium
- diuretics
- ACE inhibitors
- angiotensin-II receptor antagonists
What are some less common nephrotoxic drugs?
- bisphosphonates
- aminoglycosides
- ciclosporin or tacrolimus
- mesalazine
What mnemonic can be used to remember the common nephrotoxic drugs?
DAMN
D - diuretics
A - ACEi / ARBs / antibiotics (gentamicin)
M - metformin
N - NSAIDs
What are the typical signs and symptoms someone may present with?
CKD is usually asymptomatic until the advanced stages
signs are likely to be vague, such as:
* restless legs
* tiredness / fatigue
* nausea / vomiting
* peripheral oedema
* pruritis
these are uraemic symptoms as they are commonly caused by retention of waste products
What are the urinary symptoms of advanced CKD?
- nocturia
- increased urinary frequency
- oliguria
- persistently frothy urine is a sign of proteinuria
this happens as the kidneys fail to concentrate urine, causing production of a larger volume or dilute urine
What are the cognitive effects of CKD?
- increased risk of cognitive impairment by 65%
- cognition is affected early, but different skills decline at different rates
- language and attention particularly affected
What changes in appearance may occur?
- pallor due to secondary anaemia
- HTN is common either as a primary or secondary effect
- SOB can occur due to fluid overload, anaemia, ischaemic HD
What changes in the kidney shapes on imaging may give clues to the causes of CKD?
- bilaterally small kidneys with thinned cortices suggests intrinsic disease
- a unilateral small kidney can indicate renal arterial disease
- enlarged cystic kidneys suggest cystic kidney disease
- clubbed calyces and cortical scars suggest reflux with chronic infection / ischaemia
Why does peripheral oedema occur in CKD?
due to renal sodium retention
What general non-specific symptom is common in advanced CKD?
itch and cramps
- cramps are worse at night - likely to be due to neuronal irritation as a result of uraemia
What are the 4 different clinical effects of advanced uraemia?
- uraemia-induced platelet dysfunction
presents with easy bruising + increased GI bleeding
- uraemic pericarditis
presents with chest pain + pericardial friction rub
- uraemic neuropathy
presents with distal sensorimotor polyneuropathy
- uraemic encephalitis
presents with headache, confusion, seizures + coma
What are the resuts of an abnormal renal excretory function?
- fluid retention
resulting in HTN, peripheral oedema + pulmonary oedema
- potassium retention - leading to hyperkalaemia
- acid retention - resulting in metabolic acidosis
- phosphate retention - hyperphosphataemia
What are the effects on calcium levels that may occur in CKD?
decreased production of calcitriol (active metabolite of vit D) results in HYPOCALCAEMIA
this presents with bone pain, hyperphosphataemia, fractures, osteomalacia
What are the initial blood tests for CKD investigation?
What advice is given prior to the test?
- U&Es
- eGFR
- FBC - to look for signs of renal anaemia
- HbA1c + lipids - to manage CVD risk and look for other conditions
Do not eat meat for 12 hours before - this can falsely raise creatinine
What other investigations are performed as part of the initial investigation for CKD?
- early morning urine for urinary albumin:creatinine ratio (ACR)
- urine dipstick - to look for haematuria
- assess cardiovascular risk - BMI, BP & lifestyle
How can eGFR and ACR be used to diagnose and classify CKD?
- if results are abnormal, they must be repeated within 3 months to confirm the diagnosis
- UNLESS it is clear that reduced renal function has already been present for 3 months
- eGFR and ACR are used to classify the CKD stage
What additional tests may be performed when suspicious of bone disease?
serum calcium, phosphate, vitamin D & parathyroid hormone
also performed when there is unexplained hypo/hypercalcaemia
When might imaging be performed as an intial investigation for CKD?
renal tract USS performed when suspicious of urinary tract stones / obstruction, structural abnormalities or FH of polycystic kidney disease
How is eGFR used to stage CKD?
stage 1 and 2 only
Stage 1:
eGFR > 90 with other evidence of kidney damage
Stage 2:
eGFR mildly reduced 60 - 89, with other evidence of kidney damage
G1 & G2 ARE NOT CKD UNLESS THERE ARE OTHER SIGNS OF KIDNEY DAMAGE
How is eGFR used to stage CKD?
stage 3 - 5
Stage 3:
moderate reduction in eGFR with/without other signs of kidney damage
3a: eGFR 45-59
3b: eGFR 30-44
Stage 4:
severe reduction in eGFR 15-29 with/without other signs of kidney damage
Stage 5:
end-stage renal failure with eGFR < 15
How is urinary ACR used to stage CKD?
Stage A1:
ACR < 3 - may be normal or mildly reduced
Stage A2:
ACR 3-30 - moderately increased
Stage A3:
ACR > 30 - severely increased
proteinuria is an important marker for progression of CKD
How is eGFR calculated?
Why is it important to have repeated tests for diagnosis?
- calculated from serum creatinine, gender, age + ethnicity
- eGFR is an ESTIMATE and there is a degree of error relating to muscle mass
- inaccuracy is particularly important at borderline normal eGFR
Why can there be a degree of error relating to muscle mass when calculating eGFR?
- serum urea and creatinine can be falsely raised/low related to protein intake, muscle mass, dehydration + acute illness
repeated tests are needed - without recent high protein intake and over a 3 month period
What is the main goal of management of CKD?
as it is often irreversible, the main goal is to slow progression of the disease + limit loss of kidney function
What are the main ways in which management appraoches can slow progression of CKD?
- maintainence of good BP control
- lifestyle + diet advice
- reduction of cardiovascular risk
- optimise diabetic / hypertensive control
- treat any underlying cause
Why is it important to control BP in CKD?
What are the targets?
BP control reduces cardiovascular complications and slows progression of CKD
for non-diabetics, BP < 140/90 mmHg
for diabetics AND when ACR > 70mg/mmol, BP < 130/80 mmHg
What medication is often given first line to control BP in CKD?
ACE inhibitors - offered first line to patients with:
- diabetes + ACR > 3mg/mmol
- hypertension + ACR > 30mg/mmol
- ALL patients with ACR > 70mg/mmol
What must be done when starting a patient on an ACEi?
check U&Es within 2 weeks of starting an ACEi or changing the dose
ACEi can cause renal impairment + hyperkalaemia
What dietary advice is offered alongside ACEi in control of high BP?
dietary salt restriction to </= 6g daily
this is important in BP control and reducing fluid overload
What other lifestyle advice may be given to someone with CKD?
- weight loss, limiting alcohol & smoking cessation
- avoid OTC NSAIDs + herbal remedies
- there is a risk of acute kidney injury if there is severe intercurrent illness (e.g. dehydration)
What other medication may be offered to someone with a new diagnosis of CKD?
a statin is offered for primary prevention of CVD
this is usually atorvastatin 20mg
What immunisations are offered in CKD?
influenza - for CKD 3, 4 + 5
pneumococcal disease - for CKD 4 + 5
What advice is given to diabetics with CKD?
tight blood glucose control can reduce progression of CKD
patients with insulin-dependent diabetes may find insulin requirements decrease as CKD progresses - insulin clearance slows with progressive renal dysfunction
When might a diuretic be needed in CKD?
when dietary salt reduction is not sufficient to limit fluid overload
furosemide is often used
the effectiveness of diuretics is reduced in renal failure
thiazide diuretics are ineffective when eGFR < 30 - loop diuretic needed in this situation
How is anaemia as a result of CKD treated?
subcutaenous injections of erythropoietin
haematinics are checked before treatment + supplements given if needed (vit B12, folate, ferritin)
What is the treatment for renal bone disease in early CKD and why?
- in early CKD - 1,25-dihydroxyvitamin D is low
and parathyroid hormone is high
- treatment is with vitamin D supplementation
What is the treatment for renal bone disease in advanced CKD and why?
- in advanced CKD, there is hyperphosphataemia
- this is managed with dietary restriction and phosphate binders
after starting vitamin D and phosphate binders, calcium + phosphate levels are monitored every 3-4 months
What is the treatment for metabolic acidosis as a result of CKD?
oral sodium bicarbonate supplementation
When might you refer someone with CKD for specialist care?
- suspicion of urological cancer
- severe reduction in kidney function / accelerated progression of CKD
- uncontrolled HTN
- suspected / confirmed rare or genetic cause
- suspected renal artery stenosis
- suspected urinary tract obstructions
What is meant by end-stage renal disease?
chronic kidney damage that has progressed to such an extent that renal replacement therapy is required for survival
renal replacement therapy includes transplant or dialysis
What are the four options for treatment of ESRD?
When are these discussed with the patient?
- haemodialysis
- peritoneal dialysis
- kidney transplantation
- conservative care
dialysis is not usually needed until eGFR < 10, but options are discussed when eGFR < 20
What is the purpose of dialysis?
- it replaces the excretory role of the kidney and allows for diffusion of solutes between the blood & dialysis fluid
- it removes excess salt + water
- still need fluid + dietary restrictions + medications
How does haemodialysis work?
- the patient’s blood is filtered through an artificial kidney, which removes waste products + extra fluids
- the clean blood is then returned to the body
How often does haemodialysis need to be performed?
How is access to the circulation acheived?
it is performed 3 times a week for 4 hours
usually in hospital, but occasionally can be performed at home
it requires access to the circulation through an arteriovenous fistula / graft or central venous catheter
How does peritoneal dialysis work?
What is a major benefit to this method?
- there is diffusion of solutes between the patient’s blood in peritoneal capillaries and dialysis fluid within the peritoneal cavity
- a catheter is used to fill the abdomen with dialysis solution
- the waste products + fluid pass through the peritoneum from the blood and into the solution, which is then drained and removed after 30 to 40 minutes
many patients prefer this method as it can be used at home
What is CAPD and APD?
continuous ambulatory peritoneal dialysis (CAPD):
there are 4x 1.5-2.5 litre exchanges per day
automated peritoneal dialysis (APD):
there are several exchanges made by the machine whilst asleep at night
What are the benefits of kidney transplantation?
Where does the transplant come from?
- it has the best improvements in survival + quality of life
- kidney may be from a deceased donor, or a live donor who is related or altruistic
What are the drawbacks of kidney transplantation?
- lifelong immunosuppression is needed to prevent rejection
- transplant failure can occur after some time
- many patients are not suitable for transplants due to other conditions
- transplants are not readily available
Where is the kidney transplant inserted?
the person’s original kidneys are left in place
the 3rd kidney is situated in the lower left side of the abdomen
Why might someone opt for conservative care over dialysis/transplantation?
- these patients are often elderly / have multiple comorbidities and the benefits do not outweight the impact on quality of life
What are the complications associated with haemodialysis?
- hypotension
- bleeding
- loss of vascular access due to clotting
- risk of bacteraemia from line contamination
What are the complications of peritoneal dialysis?
- bacterial peritonitis
- hyperglycaemia (as dialysis solution has a high glucose concentration)
