Chronic Kidney Disease Flashcards
what are the functions of the kidney?
Measurement of kidney function and definition of chronic kidney disease
How do we assess for kidney disease?
- Filtration (excretory) function - remove
- Filtration (barrier) function - retain
- Anatomy - abnormality
what is glomerular filtration rate?
estimates how much blood passes through the glomeruli each minute
One method of determining GFR from creatinine is to collect urine (usually for 24 h) to determine the amount of creatinine that was removed from the blood over a given time interval
Pressure difference leads to glomerular filtration
Normal GFR = 120/min
How do you measure excretory Renal Function?
- Inulin clearance
- Isotope GFR
- 24 hour urine collection plus blood test
- GFR estimating equations
Creatinine will not be raised above the normal range until 60% of total kidney function is lost
Serum creatinine is the basic thing used to measure kidney function
Need to lose around 50% or more of GFR before you see a rise in your creatinine
There are pitfalls to using it
African Americans will have a higher serum creatinine level at any level of creatinine clearance because they have a higher muscle mass
What is the problem of the relationship between serum creatinine and GFR?
Creatinine is generated from breakdown of muscle
Not everyone has the same muscle mass
What does the relationship between serum creatinine and GFR depend on?
Age
Ethnicity
Gender
Weight
Other issues eg liver disease
What are some formulae that may be used to estimate GFR from serum creatinine?
- Cockcroft Gault = ([140-age] x weight x 1.23) / SCr x (0.85 if female)
- MDRD 4 variable equation = 175 x [SCr/88.4] -1.154 x [age] -0.203 x (0.742 if female) x (1.212 if black)
- CKD-EPI equation
How do we assess kidney excretory function?
International CKD Classification System
What things do we test for kidney disease?
- Filtration (excrete out) function – use estimates of GFR (eGFR) from creatinine blood test
- Filtration (keep in) function
- Anatomy
what things can cross the glomerular basement membrane (GBM)?
–Water
–Electrolytes
–Urea
–Creatinine
what things cross the GBM but are reabsorbed in the proximal tubule?
–Glucose
–Low molecular weight proteins (α2 microglobulin)
what things do not cross the GBM?
–Cells (RBC, WBC)
–High molecular weight proteins (albumin, globulins)
what should there be none of in the urine if it is being filtered properly?
•Should be no blood or protein measurable in urine if filtering properly
• Urinalysis (“dipstick”) can detect what in the urine?
blood
protein
How is protein quantification done?
Protein creatinine ratio (PCR)
How do we check filtration (excrete out) function?
use estimates of GFR (eGFR) from creatinine blood test
How do we assess filtration (keep in) function?
check for presence of blood or protein in urine
how do we check the anatomy?
histology
imaging
What is the current CKD definition?
• Chronic kidney disease (CKD) is defined by either the presence of kidney damage (abnormal blood, urine or x-ray findings) or GFR<60 ml/min/1.73m2 that is present for ≥3 months
Must have at least 2 samples spaced out by a couple of months to be called chronic kidney disease
Prevalence of CKD
what is the prevelance of CDK and what does it increase with?
- Increases with age
- ~8-12% UK
Why is CKD important?
does CDK cost a lot of money?
yes costs lots of money to care for a patient
Are numbers for Renal replacement therapy
(for end stage renal disease) increasing or decreasing?
Prevalent numbers on RRT are increasing every year
Numbers of dialysis not increasing over last few years due to increased transplant
what is the mortality of CDK like?
High mortality with patients with chronic kidney disease as often underlying condition hat are increased cardiac risk
Increases with worsening renal function
Aetiology of CKD
what is the aetiology of CDK?
lots of different causes
Depends on the population studied
Often difficult to establish
But if we can find out the cause…could be important to management and outcome
what is the clinical approach to dealing with CDK?
- Detection of the underlying aetiology - Treatment for specific disease
- Slowing the rate of renal decline - Generic therapies
- Assessment of complications related to reduced GFR - Prevention and Treatment
- Preparation for Renal Replacement Therapy
Clinical assessment
What are the symptoms and signs of CKD?
Mainly asymptomatic
Often incidentally picked up on blood test for things like diabetes management or in hospital
Don’t have signs till very advanced
This shows some of the things that someone may have
Detection of the underlying aetiology - how is this done?
what investigations may be used for the detection of underlying aetiology?
biopsy last, others are for when you dont know exactly what is going on
what chemistry investigations can be used to detect aetiology?
–Urea, creatinine, electrolytes (Na, K, Cl)
–Bicarbonate
–Total protein, albumin
–Calcium, phosphate
– Liver function tests
–Creatine kinase
–Immunoglobulins, serum protein electrophoresis
what haemotology investigations can be used to detect underlying aetiology?
Full blood count:
- Hb
- MCV
- MCH
- WBC
- Platelets
- % hypochromic RBCs
Coagulation screen:
- PT
- APPT
- +/- Fibrinogen
what are some urine investigations to detect aetiology?
• Urinalysis (“dipstick”):
- Blood
- Protein
• Protein quantification:
- Protein creatinine ratio (PCR)
- Albumin creatinine ratio
- 24 hour urine collection
Renal disease is often __________ – only sign may be abnormal __ or ________
asymptomatic
BP
urinalysis
one imaging technique used to detect aetiology is ultrasound, what are the positives of this? and what are the negatives?
Non-invasive
No ionising radiation
May provide information about chronicity of renal disease
No functional data
Operator dependant
what pathology technique can be used to detect aetiology?
kidney boiopsy
Management
what are some potential interventions to slowing down the rate of kidney decline?
- BP control ****most important***
- Control proteinuria (particularly ACE inhibitors / ARBs)
- Treat underlying cause
- Others
Assessment of complications related to reduced GFR - what are some potential ones?
- Acidosis
- Anaemia
- Bone disease
- CV risk
- Death & Dialysis
- Electrolytes
- Fluid overload
- Gout
- Hypertension
- Iatrogenic issues
complications ar emor elikely with a wrosening ____
eGFR
What is the management of complications related to reduced GFR?
- Acidosis - bicarb
- Anaemia – EPO and iron
- Bone disease – diet and phosphate binders
- CV risk – BP, aspirin, cholesterol, exercise, weight
- Death & Dialysis – counsel and prepare
- Electrolytes – diet and consider drugs
- Fluid overload – salt and fluid restriction, diuretics
- Gout – optimise +/- meds
- Hypertension – weight, diet, fluid balance, drugs
- Iatrogenic issues – BE AWARE
Most important thing I think about __ risk as many people will die form that before they reach end stage kidney disease
CV
What preperation may be required for end stage renal disease and renal replacement therapy
- Education & information
- Selection of modality - HD / PD ?transplant ??conservative care
- Planning access
- Deciding when to start RRT (renal replacement therapy)
- Multidisciplinary team
Summary:
- CKD is _______
- Kidney function is assessed with ___ (often estimated) in stages
- There is a ____ morbidity (RRT, CV events) and mortality
- Worse kidney _______ and more _________ is associated with worse outcomes
- Early identification and management should ____ rate of decline
- In health the kidneys contribute to many ___________ functions – loss of these with ___ leads to many complications including anaemia, acidosis and bone disease.
- Good CKD care involves the _____________ team to help manage these complications and help make choices for end stage renal disease and RRT
Summary:
- CKD is common
- Kidney function is assessed with GFR (often estimated) in stages
- There is a high morbidity (RRT, CV events) and mortality
- Worse kidney function and more proteinuria is associated with worse outcomes
- Early identification and management should slow rate of decline
- In health the kidneys contribute to many homeostatic functions – loss of these with CKD leads to many complications including anaemia, acidosis and bone disease.
- Good CKD care involves the multidisciplinary team to help manage these complications and help make choices for end stage renal disease and RRT
