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1. ARF
kidney is the only major organ that can
recover from almost complete loss of
function

2. Oliguria
 Urine output
 < 400 mL/day
 5mL/kg/day
 0.5 mL/kg/hour
 Present in about 50% of cases of ARF
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3. Anuria
Urine output
<100mL in 24 hours
Suggests complete urinary
tract obstruction
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4. Common sites of obstruction
 Normal points of narrowing
 Ureteropelvic junction
 Ureterovesical junction
 Bladder neck
 Urethral meatus
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5. Anuria
 Urinary tract obstruction
 < 5% of ARF
 Severe prerenal or intrinsic renal
diseases
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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
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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
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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
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9. AKI - Diagnostic criteria
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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
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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
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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)
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13. Creatinine clearance
 Reasonably accurate measure of GFR
 Required when renal function is near normal
 Normal serum urea or creatinine
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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
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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

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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
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17. Inulin clearance or radionuclidelabeled markers
 Highly accurate determinations of GFR can be
obtained
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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
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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.
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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
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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…………
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