Carvounis Christos P, Nisar Sabeeha, Guro-Razuman Samerah
Department of Medicine, Division of Nephrology, Nassau University Medical Center and State University of New York atStony Brook, East Meadow, New York 11554, USA.
Kidney Int. 2002 Dec;62(6):2223-9. doi: 10.1046/j.1523-1755.2002.00683.x.
Fractional excretion of sodium (FENa) has been used in the diagnosis of acute renal failure (ARF) to distinguish between the two main causes of ARF, prerenal state and acute tubular necrosis (ATN). However, many patients with prerenal disorders receive diuretics, which decrease sodium reabsorption and thus increase FENa. In contrast, the fractional excretion of urea nitrogen (FEUN) is primarily dependent on passive forces and is therefore less influenced by diuretic therapy.
To test the hypothesis that FEUN might be more useful in evaluating ARF, we prospectively compared FEUN with FENa during 102 episodes of ARF due to either prerenal azotemia or ATN.
Patients were divided into three groups: those with prerenal azotemia (N = 50), those with prerenal azotemia treated with diuretics (N = 27), and those with ATN (N = 25). FENa was low only in the patients with untreated plain prerenal azotemia while it was high in both the prerenal with diuretics and the ATN groups. FEUN was essentially identical in the two pre-renal groups (27.9 +/- 2.4% vs. 24.5 +/- 2.3%), and very different from the FEUN found in ATN (58.6 +/- 3.6%, P < 0.0001). While 92% of the patients with prerenal azotemia had a FENa <1%, only 48% of those patients with prerenal and diuretic therapy had such a low FENa. By contrast 89% of this latter group had a FEUN <35%.
Low FEUN (</=35%) was found to be a more sensitive and specific index than FENa in differentiating between ARF due to prerenal azotemia and that due to ATN, especially if diuretics have been administered.
钠排泄分数（FENa）已被用于急性肾衰竭（ARF）的诊断，以区分ARF的两个主要病因，即肾前状态和急性肾小管坏死（ATN）。然而，许多患有肾前性疾病的患者接受了利尿剂治疗，这会降低钠重吸收，从而增加FENa。相比之下，尿素氮排泄分数（FEUN）主要取决于被动因素，因此受利尿剂治疗的影响较小。
为了验证FEUN在评估ARF中可能更有用这一假设，我们前瞻性地比较了102例因肾前性氮质血症或ATN导致的ARF发作期间的FEUN和FENa。
患者分为三组：肾前性氮质血症患者（N = 50）、接受利尿剂治疗的肾前性氮质血症患者（N = 27）和ATN患者（N = 25）。仅未接受治疗的单纯肾前性氮质血症患者的FENa较低，而接受利尿剂治疗的肾前性患者和ATN组的FENa均较高。两个肾前性组的FEUN基本相同（27.9±2.4%对24.5±2.3%），与ATN组的FEUN差异很大（58.6±3.6%，P < 0.0001）。虽然92%的肾前性氮质血症患者的FENa <1%，但接受肾前性利尿剂治疗的患者中只有48%有如此低的FENa。相比之下，后一组中有89%的患者FEUN <35%。
发现低FEUN（≤35%）在区分肾前性氮质血症引起的ARF和ATN引起的ARF方面比FENa是一个更敏感和特异的指标，特别是在已使用利尿剂的情况下。
