Chronic Kidney Disease Flashcards
How do you measure excretory real function?
- Inulin clearance
- Isotope GFR
- 24hr urine collection + blood test
- GFR estimating equations
What is the relationship between creatinine and GFR?
Will not be raised above normal range until 60% of total kidney function is lost (increases with decrease GFR)
What is the problem with estimating GFR using serum creatinine?
Creatinine is generated from breakdown of muscle and not everyone has the same muscle mass.
Depends on: • Age • Ethnicity • Gender • Weight • Other issues i.e. liver disease
What are the formulae that are 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
CKD-EPI equation
What criteria is used to assess kidney excretory function??
International CKD Classification System
What are the different stages to the international’s CKD classification system to assess excretory kidney function?
Stage 1
Kidney Damage / Normal or high GFR
GFR >90
Stage 2
Kidney Damage / Mild reduction in GFR
GFR 60-89
Stage 3a / 3b
Moderately Impaired
3a GFR 45-59
3b GFR 30-44
Stage 4
Severely Impaired
GFR 15-29
Stage 5
Advanced or on Dialysis
GFR < 15
What three functions of the kidney is assessed to determined kidney disease?
Filtration (excretory) function - remove
Filtration (barrier) function - retain
Anatomy - abnormality
How is filtration (excrete) function assessed?
Uses estimated of GFR (eGFR) from creatinine blood test
What crosses and does not cross the glomerular basement membrane?
Crosses GBM (glomerular basement membrane) • Water • Electrolytes • Urea • Creatinine
Crosses GBM but reabsorbed in proximal tubule
• Glucose
• Low molecular weight proteins (α2 microglobulin)
Does not cross GBM
• Cells (RBC, WBC)
• High molecular weight proteins (albumin, globulins)
How is kidney filtering function assessed?
Should be no blood or protein measurable I urine if filtering properly
• Urinalysis (“dipstick”) - blood, protein
• Protein quantification - protein creatinine ratio (PCR)
What is the definition of CKD?
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
What is the progression of untreated CKD?
- Normal - screen for CKD risk factors
- Increased risk - CKD risk reduction
- Damage - diagnosis + treatment, treat cormorbidties
- Decreased GFR - estimate progression, treat complication, prepare for replacement
- Kidney failure - replacement by dialysis & transplant
- CKD death
What is the aetiology of CKD?
- Diabetes
- Glomerulonephritis
- Hypertension
- Renovascular disease
- Polycystic kidney disease
Describe the clinical approach to CKD
- Detect underlying aetiology -> treatment for specific disease
- Slow rate of renal decline (with generic therapies)
- Assess complications of reduced GFR
- Prep for Renal Replacement Therapy
What are the symptoms and signs of CKD?
- Dyspnoea (fluid overload, anaemia cardiomyopathy)
- Pruritus
- Haematuria
- Proteinuria
- Change to urin output (polyuria, oliguria, nocturia)
- GI: anorexia, vomiting, taste disturbance)
- Cognitive impairment
- Hypertension
- Peripheral oedema (Na retention)
How is underlying aetiology of CKD detected?
- Bloods: U+Es, FBC
- Urine tests: urine dip, PCR or ACR, 24hr collection
- Histology: renal biopsy
- Radiology
What chemistry tests are used to detect aetiology of CKD?
- Urea, creatinine, electrolytes (Na, K, Cl)
- Bicarbonate
- Total protein, albumin
- Calcium, phosphate
- Liver function tests
- Creatine kinase
- Immunoglobulins, serum protein electrophoresis
What haematology tests are used to detect aetiology of CKD?
- Full blood count
- Hb
- Mean corpuscular volume (MCV) - average volume of red cells
- Mean corpuscular haemoglobin (MCH) - average mass of haemoglobin per RBC
- WBC
- Platelets
- % hypochromic RBCs
Coagulation screen:
• Prothrombin Time
• Activated partial thromboplastin time (APPT)
• +/- Fibrinogen
What urine tests are used to detect aetiology of CKD?
Urinalysis (“dipstick”)
• Blood
• Protein
Protein quantification
• Protein creatinine ratio (PCR)
• Albumin creatinine ratio
• 24 hour urine collection
What imaging tests are used to detect aetiology of CKD?
USS: may provide information about chronicity of renal disease and show obstruction
What pathology tests are used to detect aetiology of CKD?
Kidney biopsy
What is the management of CKD to slow the rate of renal decline using potential interventions?
- BP control *most important
- Control proteinuria (particularly ACE inhibitors / ARBs)
- Treat underlying cause
What are the complications that can occur with reduced GFR?
- Acidosis
- Anaemia
- Bone disease
- CV risk
- Death & Dialysis
- Electrolyte disturbance
- Fluid overload
- Gout
- Hypertension
- Iatrogenic issues
What is the management of the complication that occur due to reduced GFR?
- Acidosis -> bicarbonate
- 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
What is involved in the prep 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 Recommended Replacement Time
• Multidisciplinary team
