Acute Renal Failure - Tovbin

Question 1

What are the stages of AKI?

Answer 1

RIFLE:

1. Risk
   GFR <75 % or Urine output<0.5 ml/kg/hour for >6 h
   2.Injury
   GFR decreased < 50 % or Urine output<0.5 ml/kg/hour for >12 h
2. Failure
   GFR > 25 % or Urine output<0.3 ml/kg/hour for >24 h
   or Anuria for > 12
3. Loss
   After 1 month of renal failure
4. End-stage

Question 2

Acute complications of acute renal failure

Answer 2

Uremia
Pericarditis - Pericardial Effusion- Tamponad
Encephalopathy- flapping tremor, change in consciousness
Hyperkalemia
Metabolic Acidosis
Volume overload –> pulmonary edema

Question 3

How to diagnose acute renal failure

Answer 3

Plasma creatinine>1.5 (risk)

Accumulation of
Nitrogenous Waist Products –> Serum urea Creatinine all increase
K high
H+ high
Urine Output Changes– Usually decreased
Volume overload
– Oliguria<500 ml/Day
– Anuria= No Urine Output
– oligoanuria-= 100-200

Small kidneys (or normal in diabetics)

Phosphotemia

Question 4

Causes of prerenal ARF

Answer 4

Increased Renin –> Increased Angiotensin II –> Increased Aldosterone
Increased ADH
Increased Catecholamines
Increased Renal nerves activation

Question 5

Intrarenal causes of AKI

Answer 5

In Proximal Tubule:
Increased angiotensin II
Peritubular capillary increased oncotic/decreased hydrostatic pressure –> Increased Na, water and urea absorption

Distal tubule:
Aldosterone and ADH increased
Peritubular capillary increased oncotic/decreased hydrostatic pressure –> Increased Na and water absorption

Question 6

Na and Urea Absorption and excretion relative to AKI

Answer 6

Fraction of excreted Na = u/p Na / u/p Cr * 100. If ,1% then prerenal

If <1%: Prerenal

If >2%: Intrarenal

FeUrea = u/p Urea / u/p Cr * 100. <30% is prerenal

Complicating factors:
In severe GI disease, Urea would be masked by decreased potassium delivery to the blood, or if liver is not making urea
Rhabdomyolysis or lab error show increased mucle breakdown and huge jump in Cr

Question 7

Aminoglycoside Nephrotoxicity

Answer 7

Bacteriocidal antibiotic, dangerous to give if kidneys impaired

Renally Cleared
Drug Concentration in Proximal Loop Lysosoms
Impaired ATP Production
Renal Failure After 1-2 Weeks
Earlier in presence of Ischemia
Non-oliguric- Usually

Over dosage
– GFR Overestimation (missed unless Cr checked)
– Undiagnosed ARF
Can appear with normal levels
Risk Factors
– Volume Depletion
– Liver Disease
– Renal Failure
– CHF