Definition: Oliguria that is caused by hypoperfusion of the kidneys
Causes: Most commonly due to hypovolemia (check a CVP); however, must also consider other causes such as cardiogenic shock, sepsis, acute blood loss.
- Urinary sodium should be less than 20 as it is the kidney’s response to low perfusion
- It may also be prudent to calculate a FENa or fractional excretion or sodium or FEUrea *fractional excretion of urea* (if the pt. has been on diuretics)
(FENa) = (PCr * UNa ) / (PNa x UCr) % FEUrea – (FEUrea) = (SerumCr * UUrea ) / (SerumUrea x UCr) %
The etiology is most likely pre-renal if:
- The FENa is less than 1%
- The FEUrea is low i.e. <35
Treatment: The mainstay of treatment is correction of the underlying cause: hypovolemia (fluid resuscitation), hypotension (inotropes or vasopressors), sepsis (antibiotics and vasopressors), acute blood loss (transfusion and/or fluid resuscitation).