Guidelines for Urinary Indices in Acute Renal Failure (ARF)

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
ARF
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
casts
Renal tubular epithelial cells;
granular and muddy brown casts

Osm, osmole; Eq, equivalent.
 
 
References:

  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

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