Chronic Kidney Disease Flashcards
What are some functions of the kidneys?
Body fluid homeostasis
Endocrine function
Acid-base homeostasis
Electrolyte homeostasis
Excretory function
Regulation of vascular tone
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How do we assess for kidney disease?
- Filtration (excretory) function
- Remove
- Tested by using estimates of GFR (eGFR) from creatinine blood test
- Filtration (barrier) function
- Retain
- Tested by checking presence of blood or protein in urine
- Anatomy
- Abnormality
- Tested by histology or imaging
What causes glomerular filtration?
Pressure differences
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How do you measure excretory renal function?
- Insulin clearance
- Isotope GFR
- 24 hour urine collection plus blood test
-
GFR estimating equations (most commonly used in clinical practice)
- Creatinine
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What is a problem with using creatinine to estimate GFR?
A problem with using creatinine is it is generated from the breakdown of muscle, and not everyone has the same muscle mass, it also depends on:
- Age
- Ethnicity
- Gender
- Weight
- Other issues such as liver disease
What are some different formulae used to estimate GFR from serum creatinine?
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What is used to stage kidney disease?
International chronic kidney disease (CKD) classification
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What does CKD stand for?
Chronic kidney disease
What % is GFR of normal in stage 1 chronic kidney disease?
>90%
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What % is GFR of normal in stage 2 chronic kidney disease?
60-89%
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What % is GFR of normal in stage 3a chronic kidney disease?
45-59%
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What % is GFR of normal in stage 3b chronic kidney disease?
30-44%
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What % is GFR of normal in stage 4 chronic kidney disease?
15-29%
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What % is GFR of normal in stage 5 chronic kidney disease?
<15%
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What does GBM stand for?
Glomerular basement membrane
Do all substances cross the GBM?
Not all substances cross the glomerular basement membrane (GBM):
- Crosses GBM
- Water
- Electrolytes
- Urea
- Creatinine
- Crosses GBM but reabsorbed in proximal tubule
- Glucose
- Low molecular weight proteins (a2-microglobulin)
- Does not cross GBM
- Cells (RBC, WBC)
- High molecular weight proteins (albumin, globulins)
What are examples of substances that cross the GBM?
- Water
- Electrolytes
- Urea
- Creatinine
What are examples of substances that cross the GBM but are reabsorbed in proximal tubule?
- Glucose
- Low molecular weight proteins (a2-microglobulin)
What are examples of substances that do not cross the GBM?
- Cells (RBC, WBC)
- High molecular weight proteins (albumin, globulins)
Should there be any blood measurable in the urine?
There should be no blood or protein measurable in urine if filtering properly
What investigations can be done to test the filtering function of the kidneys?
What investigation is a “dipstick”?
Urinalysis
What is checked for in urinalysis?
Blood
Protein
What does PCR stand for?
Protein-creatinine ratio
What is chronic kidney disease (CKD)?
Defined by either presence of kidney damage (abnormal blood, urine or x-ray findings) or GFR <60ml/min/1.73m2 that is present for 3 or more months
What are the different categories of albuminuria?
A1
A2
A3
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What is the medical term for excess albumin in urine?
Albuminuria
What is A1 albuminura?
Nomal to mildly increased
<30mg/g
<3mg/mmol
What is A2 albuminuria?
Moderately increased
30-300mg/g
3-30mg/mol
What is A3 albuminuria?
Severely increased
>300mg/g
>30mg/mol
What is the prevalence of chronic kidney disease (CKD)?
About 8-12% in UK
Increases with age
Who is renal replacement therapy given to?
People for end stage renal disease
What is the aetiology of CKD?
- Polycystic kidney disease
- Diabetes
- Glomerulonephritis
- And all the causes of that
- Hypertension
- Renovascular disease
Explain the clinical approach to CKD?
- Detection of the underlying aetiology
- Treatment for specific disease
- Slowing rate of renal decline
- Generic therapies
- Assessment of complications related to reduced GFR
- Prevention and treatment
- Preparation for renal replacement therapy
What is the clinical presentation of CKD?
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What are important parts of the history for CKD?
- Previous evidence of renal disease
- Family history
- Systemic diseases
- Drug exposure
- Pre/post renal factors
- Uraemic symptoms
What are important parts of the examination for CKD?
- Vital signs
- Volume status
- Systemic illness
- Obstruction
What investigations are done for chronic kidney disease (CKD)?
- Blood tests
- U and Es, FBC
- Urine tests
- Urine dip, urine PCR or ACR (24-hour collection)
- Histology
- Renal biopsy
- Radiology
What investigations can be done to detect the aetiology of CKD?
- Chemistry
- Urea, creatinine, electrolytes (Na, K, Cl)
- Bicarbonate
- Total protein, albumin
- Calcium, phosphate
- Liver function tests
- Creatine kinase
- Immunoglobulins, serum protein electrophoresis
- Haematology
- Full blood count
- Hb
- MCV
- MCH
- WBC
- Platelets
- % of hypochromic RBCs
- Coagulation screen
- PT
- APPT
- With or without fibrinogen
- Full blood count
- Urine investigations
- Urinalysis (“dipstick”
- Blood
- Protein
- Protein quantification
- Protein creatinine ratio (PCR)
- Albumin creatinine ratio
- 24 hour urine collection
- Urinalysis (“dipstick”
- Imaging
- US
- Advantages
- Non-invasive
- No ionising radiation
- May provide information about chronicity of renal disease
- Disadvantages
- No functional data
- Operator dependant
- Advantages
- US
- Pathology
- Kidney biopsy
What are advantages of an ultrasound scan?
- Non-invasive
- No ionising radiation
- May provide information about chronicity of renal disease
What are disadvantages of an ultrasound scan?
- No functional data
Operator dependant
What are some potential interventions to slow the rate of decline of GFR in CKD?
- BP control (most important)
- Control protein urea
- Particular ACE inhibitors/ARBs
- Treat underlying causes
What are some complications related to reduced GFR?
- Acidosis
- Anaemia
- Bone disease
- CV risk
- Death and dialysis
- Electrolytes
- Fluid overload
- Gout
- Hypertension
- Iatrogenic issues
What are some ways to prepare patients for end-stage renal disease and renal replacement therapy?
- Education and information
- Selection of modality
- HD/PD, transplant, conservative care
- Planning access
- Deciding when to start renal replacement therapy (RRT)
- MDT