ARF
kidney is the only major organ that can
recover from almost complete loss of
function
Oliguria
 Urine output
 < 400 mL/day
 5mL/kg/day
 0.5 mL/kg/hour

 Present in about 50% of cases of ARF

2

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Anuria
Urine output
<100mL in 24 hours
Suggests complete urinary
tract obstruction

3

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Common sites of obstruction
 Normal points of narrowing
 Ureteropelvic junction
 Ureterovesical junction
 Bladder neck...
Anuria
 Urinary tract obstruction
 < 5% of ARF

 Severe prerenal or intrinsic renal

diseases

5

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Anuria – less common causes
1) Total renal artery or vein occlusion
2) Shock with severe hypotension and intense

renal va...
Acute kidney injury
 Reduction in kidney function in < 48 hours

manifested by any one of the following
 Absolute increa...
Disadvantages
 Depending on serum creatinine level and

urine output
 Abrupt fall in GFR to nearly zero
 Serum creatini...
AKI - Diagnostic criteria

9

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Serum creatinine
 Production is remarkably constant
 Mainly from muscle cells

 Little affected by protein intake
 GFR...
FACTORS AFFECTING UREA
PRODUCTION
Production increased by
 High-protein diet
 Increased catabolism – Surgery, Infection,...
Serum creatinine
 Decreased
 Low muscle mass

 Increased
 High muscle mass
 Red meat ingestion
 Muscle damage (rhabd...
Creatinine clearance
 Reasonably accurate measure of GFR

 Required when renal function is near normal
 Normal serum ur...
Measurement of true GFR is time
consuming
 24 hours urine
 For urinary creatinine
 Inaccurate if 24-hour urine collecti...
Cockroft-Gault formula
To predict creatinine clearance (GFR) from
serum creatinine
 Takes into account the patient's age,...
Cockroft-Gault formula
 Creatinine clearance (men) =

(140 – age) X body weight in kgs
Plasma creatinine in mg% X 72

Thi...
Inulin clearance or radionuclidelabeled markers
 Highly accurate determinations of GFR can be

obtained

17

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Cystatin C
 Endogenous cysteine protease

inhibitor
 Produced at a constant rate
 Low-molecular-weight protein
 Filter...
Cystatin C
 More sensitive to mild renal impairment
 Particularly when the creatinine is still normal
 May detect AKI 1...
Retinol-binding protein and β2microglobulin
 Normally reabsorbed by the proximal tubule
 Increased Urinary excretion
 D...
Kidney injury molecule-1
 Transmembrane protein
 Present when proximal tubular cells are injured
 Not expressed in the ...
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Acute Renal Failure

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Acute Renal Failure

  1. 1. ARF kidney is the only major organ that can recover from almost complete loss of function
  2. 2. Oliguria  Urine output  < 400 mL/day  5mL/kg/day  0.5 mL/kg/hour  Present in about 50% of cases of ARF 2 www.medicinemcq.com
  3. 3. Anuria Urine output <100mL in 24 hours Suggests complete urinary tract obstruction 3 www.medicinemcq.com
  4. 4. Common sites of obstruction  Normal points of narrowing  Ureteropelvic junction  Ureterovesical junction  Bladder neck  Urethral meatus 4 www.medicinemcq.com
  5. 5. Anuria  Urinary tract obstruction  < 5% of ARF  Severe prerenal or intrinsic renal diseases 5 www.medicinemcq.com
  6. 6. Anuria – less common causes 1) Total renal artery or vein occlusion 2) Shock with severe hypotension and intense renal vasoconstriction 3) Rapidly progressive glomerulonephritis 4) Acute bilateral cortical necrosis a) Septic abortions b) Abruptio placentae c) Preeclampsia 5) Acute tubular necrosis 6 www.medicinemcq.com
  7. 7. Acute kidney injury  Reduction in kidney function in < 48 hours manifested by any one of the following  Absolute increase in serum creatinine level of 0.3 mg/dL or more  Relative increase in serum creatinine level of 50% or more  Oliguria of less than 0.5 mL/kg/h for more than 6 hours despite adequate fluid resuscitation 7 www.medicinemcq.com
  8. 8. Disadvantages  Depending on serum creatinine level and urine output  Abrupt fall in GFR to nearly zero  Serum creatinine concentration may not rise significantly for 1 to 2 days 8 www.medicinemcq.com
  9. 9. AKI - Diagnostic criteria 9 www.medicinemcq.com
  10. 10. Serum creatinine  Production is remarkably constant  Mainly from muscle cells  Little affected by protein intake  GFR  Directly related to the urine creatinine excretion  Inversely related to the serum creatinine  Better indicator of renal function than urea 10 www.medicinemcq.com
  11. 11. FACTORS AFFECTING UREA PRODUCTION Production increased by  High-protein diet  Increased catabolism – Surgery, Infection, Trauma  Gastrointestinal bleeding Production decreased by  Low-protein diet  Reduced catabolism, e.g. old age  Liver failure Elimination decreased by  Glomerular disease  Reduced renal blood flow – Hypotension, Dehydration 11 www.medicinemcq.com
  12. 12. Serum creatinine  Decreased  Low muscle mass  Increased  High muscle mass  Red meat ingestion  Muscle damage (rhabdomyolysis)  Decreased tubular secretion (e.g. cimetidine, trimethoprim therapy) 12 www.medicinemcq.com
  13. 13. Creatinine clearance  Reasonably accurate measure of GFR  Required when renal function is near normal  Normal serum urea or creatinine 13 www.medicinemcq.com
  14. 14. Measurement of true GFR is time consuming  24 hours urine  For urinary creatinine  Inaccurate if 24-hour urine collections are incomplete  Single plasma level of creatinine  Measured some time during the 24-hour period 14 www.medicinemcq.com
  15. 15. Cockroft-Gault formula To predict creatinine clearance (GFR) from serum creatinine  Takes into account the patient's age, gender, weight and plasma creatinine  Used mostly to adjust the dose of drugs  15 www.medicinemcq.com
  16. 16. Cockroft-Gault formula  Creatinine clearance (men) = (140 – age) X body weight in kgs Plasma creatinine in mg% X 72 This value should be multiplied 0.85 for women, since a lower fraction of the body weight is composed of muscle 16 www.medicinemcq.com
  17. 17. Inulin clearance or radionuclidelabeled markers  Highly accurate determinations of GFR can be obtained 17 www.medicinemcq.com
  18. 18. Cystatin C  Endogenous cysteine protease inhibitor  Produced at a constant rate  Low-molecular-weight protein  Filtered freely by the glomerulus  Not secreted by tubules  Correlates with GFR 18 www.medicinemcq.com
  19. 19. Cystatin C  More sensitive to mild renal impairment  Particularly when the creatinine is still normal  May detect AKI 1–2 days earlier than serum creatinine. 19 www.medicinemcq.com
  20. 20. Retinol-binding protein and β2microglobulin  Normally reabsorbed by the proximal tubule  Increased Urinary excretion  Diseases of the proximal tubule  Early marker of tubular dysfunction in a variety of conditions 20 www.medicinemcq.com
  21. 21. Kidney injury molecule-1  Transmembrane protein  Present when proximal tubular cells are injured  Not expressed in the absence of tubular injury or in extrarenal tissues………… for rest of the slides visit ww.medicinemcq.com > Nephrology 21 www.medicinemcq.com
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