Use of the Fractional Excretion of Urea in an Azotemic Nonoliguric State: Type 1 Cardiorenal Syndrome

Abstract

The fractional excretion of urea is a useful tool to evaluate renal function in oliguric states; however, it remains unexplored in nonoliguric states. We evaluated its use to predict responses in patients with type 1 cardiorenal syndrome. This was a prospective observational study of 116 patients with type 1 cardiorenal syndrome referred over a 4-year period. Fractional excretion of urea and sodium, ejection fraction, mean arterial pressure, age, sex, diabetes, brain natriuretic peptide (BNP), serum sodium and blood urea nitrogen were analyzed for effects upon serum creatinine and survival. Improvement of renal function correlated most significantly with FeUrea (P = 0.00001) followed by the FeNa (P = 0.005) but no other variable studied reached significance. Survival was best predicted by improvement of the serum creatinine at 24 h (P = 0.005) and 7 days after all inotropes were stopped (P = 0.001). A limitation of this study is that it cannot be extrapolated to all cardiorenal syndrome patients other than type 1. Also, the study was not randomized and those with potentially worse disease have had worse outcomes due merely to worse underlying disease. The success of the FeUrea may possibly be related to interference of dobutamine on creatinine levels. Despite being a nonoliguric state, the FeUrea appears to provide insight to those patients with type 1 cardiorenal syndrome whose renal function (as measured by serum creatinine) and survival might improve.

Bedside Prognostication in Decompensated Heart Failure: No “Easy Button”

“… 7 It has found application in type 1 cardiorenal syndrome as a prognostic indicator of renal function recovery as well as overall survival. 8 Indeed, the present authors showed in a previous publication that low FEUN in this cohort of patients with ADHF was associated with a nearly 50% increase in postdischarge all‐cause death, independently of other heart failure risk factors. 9 Compromised renal perfusion in the setting of ADHF can lead to poor outcomes, but clinicians are often faced with the conundrum that diuretics have either caused excessive intravascular volume depletion or failed to maintain the higher filling pressures required to preserve cardiac output as Frank‐Starling reserve is lost.…”

Pediatrik Akut Böbrek Hasarında Fraksiyone Üre Ekskresyonu

“…AKI is an important problem to assess. Mortality in patients with AKI increases along with the increase in serum creatinine (4). The Risk, Injury, Failure, Loss, and End-stage kidney disease (RIFLE) classification determines the grade of AKI based on serum creatinine level or glomerular filtration rate (GFR) and urine output (5).…”