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29 Cards in this Set

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  • Back
What are the 3 cause categories of acute renal failure?
1) pre-renal (deficient kidney perfusion)

2) renal (kindey damage, e.g. ATN, GN)

3) post-renal (damage outside kidney, e.g. uretal obstruction)
What are the 4 phases of acute renal failure?
1) Initiating
2) Oliguric
3) Diuretic
4) Recovery
What is the definition of ARF?
Rapid deterioration in renal function over the course of days to weeks, resulting in the accumulation of nitrogenous waste (BUN-azotemia).
What is the most common cause of ARF in the outpatient setting?
Pre-renal Azotemia
What part of the kidney is most affected by underperfusion with Pre-renal azotemia?
outer medulla (uses 80% of oxygen and therefore has little reserve)
What are the 2 main causes of acute tubular necrosis?
1) ischemia to the outer medulla (60%), e.g.PRA

2) toxicity (40%), usually pars convoluta of the PT is involved

ATN is usually secondary to some other illness.
What is the mortality rate for ATN?
Name 4 causes for an elevated BUN with normal renal function.
1) increased protein intake
2) corticosteroids
3) GI bleed
4) catabolism
Name 3 things that can cause an elevated serum creatine level with normal renal function.
1) decreased PT secretion (Bactrim, Cimetidine)
2) increased production (rhabdomyolysis from cocaine, trauma, statins, seizures)
3) increased protein intake
How is renal function assessed?
1) serum creatinine
2) creatinine clearance
3) Cockroft and Gault formula
4) iothalmate clearance (nuclear radiology study)
Trace the path of creatinine from origin to end.
1) Creatine is produced in the liver (or ingested) and stored in the muscle.

2) It then gets metabolized in the muscle into creatinine and released into the bloodstream

3) most of the creatinine gets filtered in the kidneys. However, 15% is secreted.
What is the cutoff point for serum creatinine levels in men? in women?
men < 1.5 mg/dL
women < 1.2 mg/dL
At what serum creatinine level does the greatest loss of renal function occur:
a) 1-2 mg/dL
b) 2-3 mg/dL
c) 3-4 mg/dL
d) 4-5 mg/dL

a) 1-2 mg/dL 50%
b) 2-3 mg/dL 17%
c) 3-4 mg/dL 8%
d) 4-5 mg/dL 5%
The absolute value of the serum creatinine is variable so that an absolute value of _______ is needed to be confident that a real change of renal function has occurred. What are some exceptions to this rule of thumb?
0.5 mg/dL

exceptions w/depressed protein levels:
1) cirrhosis
2) pregnancy
3) extremes of age/nutrition
State the clearance formula used with complete 24hour urine collection.
Clearance = [(Urine concentation)*(urine volume)]/plasma concentration
= ml/min
How many minutes are there in a day?
1440 minutes/day
What is the Cockroft and Gaul Formula?
Best formula for calulating GFR as it take into account age, weight and sex.

GFR = (140-age)*wgt in kg/(72*Cr)

Multiply by 0.85 for women
What is the normal BUN/Cr ratio?
What does a BUN:Cr < 10:1 mean?
a) Increased Cr production from rhabdomyolysis

b) increased protein intake

c) impaired tubular secretion (Bactrim, Cimetidine)
What does a BUN:Cr = 10:1 mean?
normal function or ATN (if FENA also high >3%)
What does a BUN:Cr > 10:1 mean?
pre-renal azotemia

also possible with:
a) corticosteroids
b) GI bleed
c) catabolism
d) increased protein intake
A change in CLcr of ___% or a CLcr of <_____ml/min is indicative of ARF.
25 %
90 ml/min
What is the most common in-hospital form of ARF?
acute tubular necrosis
What are 4 possible causes of the loss of volume seen in pre-renal azotemia?
1) absolute volume depletion (e.g. vomiting, sweating, diarrhea, hemorrhage, fistula)

2) relative depletion (3rd spacing; hypoalbuminemia, pancreatitis, burns, sepsis)

3) impaired CO (cardiomyopathy, valvulat diz, MI, tanponade, pulmonary HTN)

4) Abnormal auto-regulation (ACE-I, ARB, NSAID
With PRA what are expected values for the following:
a) urine Na+
c) BUN:Cr
d) S.G.
e) Urine Osmolarity
f) Casts
Sodium Avid state

a) urine Na+ : < 20 mEq/L
b) FENA : <1%
c) BUN:Cr >20:1
d) S.G.: >1.010
e) Urine Osmolarity: >500 mosm
f) Casts: hyaline (normal) or none
What is FENA?
Fractional Excretion of Na+ = ((Una/Pna)/(Ucr/Pcr))*100%
In which high risk patients with PRA should NSAIDS never be given (and ACE-I and ARB closely monitored)?
- cirrhosis
- nephrotic syndrome
- bilateral renal vascular disease (e.g. renal artery stenosis)
What are common causes of toxic ATN?
1) aminoglycosides
2) IV contrast
3) heme pigments
4) light chains
5) amphotericin
6) CIs platinum
With Acute Tubular Necrosis what are expected values for the following:
a) urine Na+
c) BUN:Cr
d) S.G.
e) Urine Osmolarity
f) Casts
Can't reabsorb Na+ due to damage:

a) urine Na+: >40mEq/L
b) FENA: >3%
c) BUN:Cr 10-15:1
d) S.G. = 1.010 (isothenuria)
e) Urine Osmolarity: 280mosm
f) Casts : granular or muddy