Prerenal Kidney Failure: Sensitivity and Specificity

Introduction: Acute kidney failure is generally divided into 3 categories: renal, pre-renal, and post-renal causes. Pre-renal causes are those that result from hypoperfusion of the kidneys, principally hypovolemia and cardiogenic shock.

The most common causes of ARF are prerenal failure and ATN.

Another reference study is Ann Intern Med. 1978 Jul;89(1):47-50 PMID: 666184.

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The sensitivity and specificity of findings for Prerenal Kidney Failure are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Blood Test
Finding	Result	Sensitivity	Specificity
[ + ] Elevated BUN to Creatinine Ratio	+ 0 -	87%	80%
ratio >15 including patients on diuretics. Patients with diuretics only had sens = 85%. Study: Kidney Int. 2002 Dec;62(6):2223-9. PMID: 12427149

Urine Test
Finding	Result	Sensitivity	Specificity
[ + ] Fractional Excretion of Urea	+ 0 -	89.6%	96%
FEurea < 35% including patients on diuretics. Patients with diuretics only had sens = 88.9%; without diuretics sens = 90%. Study: Kidney Int. 2002 Dec;62(6):2223-9. PMID: 12427149

Untagged
Finding	Result	Sensitivity	Specificity
[ + ] Fractional Excretion of Sodium	+ 0 -	76.6%	96%
ratio < 1% including patients on diuretics. Patients with diuretics only had sens = 48%; without diuretics sens = 92%. Study: Kidney Int. 2002 Dec;62(6):2223-9. PMID: 12427149
[ + ] Urine Creatinine to Plasma Creatitine Ratio	+ 0 -	80.5%	88%
including patients on diuretics. Patients with diuretics only had sens = 63%. Study: Kidney Int. 2002 Dec;62(6):2223-9. PMID: 12427149
[ + ] Urine Sodium to Potassium Ratio	+ 0 -	66.2%	92%
ratio < 1 including patients on diuretics. Patients with diuretics only had sens = 41%. Study: Kidney Int. 2002 Dec;62(6):2223-9. PMID: 12427149