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Fractional excretion of urea as a diagnostic index in acute kidney injury in intensive care patients
Journal of Critical Care, 04/23/2012
Dewitte A et al. – Fractional excretion of urea less than 40% was found to be a sensitive and specific index in differentiating transient from persistent acute kidney injury (AKI) in intensive care unit patients especially if diuretics had been administered.
Methods- This was an observational study.
- Forty-seven patients with AKI according to the RIFLE classification were included.
- Transient AKI was defined as AKI resolved within 3days after inclusion.
- Persistent AKI was defined as persistent serum creatinine elevation or oliguria.
- Fractional excretion of urea was lower in case of transient, 33% (25-39), than persistent AKI, 47% (36-61) (P=.001).
- Areas under the receiver operating characteristic curve for FeU in case of transient AKI were better than those for other urinary indexes, 0.78 (95% confidence interval, 0.63-0.92).
- Optimal cutoff point according to the receiver operating characteristic curve was 40%.
- In patients treated with diuretics, FeU was the only predictive index of transient AKI.
- Fractional excretion of urea gradually increased from days 1 to 7 in transient AKI, whereas plasma creatinine decreased.
