What are the urinary findings in AKI resulting from sepsis?
The urinary findings are highly variable in this setting. Studies have shown either a high or low fractional excretion of sodium or urea and either high or low urinary osmolalities.
This wide range of findings likely reflects the timing of the urine studies in relation to the amount of irreversible injury versus hemodynamic factors (i.e., the fractional excretion of sodium may be initially low when the mechanism of acute kidney injury results from vasoconstriction but may be elevated in the setting of tubular injury).
The most common findings on urine microscopic examination are granular (“muddy brown”) casts that represent shedding and degradation of tubular cells. However, the absence of these casts does not exclude the diagnosis of acute kidney injury.
