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:
- 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
