4. Common sites of obstruction
Normal points of narrowing
Ureteropelvic junction
Ureterovesical junction
Bladder neck
Urethral meatus
4
www.medicinemcq.com
5. Anuria
Urinary tract obstruction
< 5% of ARF
Severe prerenal or intrinsic renal
diseases
5
www.medicinemcq.com
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. 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. 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
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. 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. 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. Creatinine clearance
Reasonably accurate measure of GFR
Required when renal function is near normal
Normal serum urea or creatinine
13
www.medicinemcq.com
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. 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. 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. Inulin clearance or radionuclidelabeled markers
Highly accurate determinations of GFR can be
obtained
17
www.medicinemcq.com
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. 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. 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. 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