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Fractional Excretion of Sodium
Gerald Hurowitz, M.D.Published 22 February 20051 min read
Fractional Excretion of Sodium (FENa) = (UNa x PCr) / (PNa x UCr) x 100
Renal Failure Index (RFI) = (UNa x PCr) / UCr
Interpretation of the Urinary Indices
| Prerenal | ATN | Postrenal | |
| UNa (mmol/L) | < 20 | > 40 | > 40 |
| FENa | < 1% | > 1% | > 4% |
| RFI | < 1% | > 1% | > 1% |
Written and revised by
Gerald Hurowitz, M.D.
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