Section 1: Epidemiology and CKD

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Section 1 Epidemiology and CKD
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The Problem

• Chronic Kidney Disease is an epidemic worldwide
• Growth 6-8 per annum of dialysis patients
• Accumulating data re possibility of delaying the
  progression of kidney disease, using multiple
  drug and behaviour intervention therapies.
• Under-recognition at earlier stages of kidney
  dysfunction persists
• Late referral
• Lost opportunities for improved patient outcomes
•  

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Prevalence of ESRF
UK Renal Registry
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Section 2 Measurement of Kidney Function
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What Tests Are Available?
Accurate

• Direct GFR measurement
• Inulin clearance
• Radionuclides
• Iohexol clearance
• 3 hr CrCl with Cimetidine
• Prediction equations
• Cystatin C
• 24 hr urine CrCl
• Serum creatinine

Inaccurate
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Gold Standards

• Inulin clearance
• Tedious, time consuming unavailable
• Radionuclides
• 125Iodine-iothalamate, technetium DTPA,
  51Chromium-EDTA clearance
• Time consuming and expensive
• Research, accurate drug dosing

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Serum Creatinine Problems

• Non-renal influences
• Gender, ethnicity, age and muscle mass
• Nutrition/diet
• Drugs (e.g. cimetidine)
• Clinical utility
• Poor sensitivity for CKD
• Not useful in ARF
• Muscle wasting disorders and amputees
• Analytical problems
• Non-specificity (protein, ketones, ascorbic acid)
• No international standardization
• Spectral interferences (icterus/lipaemia/haemolysi
  s)

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Serum CreatinineHides Early Renal Damage
600
400
Serum creatinine (µmol/L)
200
Proportion misdiagnosis
0
GFR (mL/min/1.73m2)
Reproduction from the late David Newman
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Glomerular Filtration Rate

• Sum of all nephron filtration rates
• Best index of overall function
• Reduction implies a problem
• Translatable concept
• Equates to percentage Kidney function

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GFR Prediction Equations

• Cockcroft-Gault formula
• Ccr (ml/min) 1.23 x (140-age) x weight/Pcr
• (x 0.85 if female)
• MDRD Study equation
• GFR (ml/min/1.73 m2) 186 x
  (Pcr)/88.4-1.154 x (age)-0.203 x (0.742 if
  female) x (1.210 if African American)

Cockcroft Gault. Nephron 1976 16 31-41 Levey
AS, et al. Ann Intern Med 1999130 461-70
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MDRD equation vs serum creatinine
220 200 180 160 140 120 100 80
220 200 180 160 140 120 100 80
Females
Males
sCr (µmol/L)
79.4
98.4
sCr (µmol/L)
27.7
81
30 40 50 60
30 40 50 60
eGFR (ml/min/1.73m2)
eGFR (ml/min/1.73m2)
Middleton et al 2004
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Scatter Increases as GFR Approaches
Physiological Levels
Froissart et al JASN 200516763-773
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MDRD Formula validation
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Section 3CKD classification and prevalence
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Estimates of Prevalence of CKD in the US NHANES
III
Adapted from Am J Kidney Dis 2002 39 (2, Suppl.
1) S17-S31
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Stages of CKD by GFR
It is helpful to think of GFR (mL/min/1.72m2)
as an approximation of Kidney function
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Prevalence CKD
Source NHANES
Stevens et al, EDTA-ERA Lisbon 2004
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CKD A Typical GP Practice of 10000
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6
15
4
60
Stage of Kidney Disease
30
(GFR)
380
3
60
2
460
90
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