Guidelines for Urinary Indices in Acute Renal Failure (ARF)

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Guidelines for urinary indices whereby established Acute Renal Failure (ARF) can be distinguished from renal vasoconstriction with intact tubular function (prerenal azotemia).

Laboratory test
Prerenal azotemia
Urine osmolality (mOsm/kg) >500 <400
Urine sodium level (mEq/l) <20 >40
Urine/plasma creatinine ratio >40 <20
Urine/plasma urea ratio >8 <3
Fractional excretion of sodium (%) <1 >2
Fractional excretion of urea (%) <35 >35
Urinary sediment Normal;
occasional hyaline
or fine granular
Renal tubular epithelial cells;
granular and muddy brown casts

Osm, osmole; Eq, equivalent.




  1. Schrier RW, Wang W, Poole B, Mitra A. Acute renal failure: definitions, diagnosis, pathogenesis, and therapy. J Clin Invest. 2004 Jul;114(1):5-14. [Medline]

Created: Jun 12, 2009