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renal failure index (RFI)
Defined as:
(urine Na+ x urine creatinine) / urine creatinine
Indications:
- acute renal failure
- prerenal azotemia
- acute tubular necrosis
Clinical significance:
- useful for distinguishing prerenal azotemia from intrinsic renal disease in patients with acute renal failure (ARF):
- index (RFI)
- < 0.01 (or 1%): prerenal
- > 0.01 (or 1%): renal
General
urinary indices
References
Saunders Manual of Medical Practice, Rakel (ed),
WB Saunders, Philadelphia, 1996, pg 536-37