Fractional Excretion of Urea in Pediatric Patients with Acute Kidney Injury

Year 2023, Volume: 17 Issue: 2, 91 - 95, 22.03.2023

Özlem Yüksel Aksoy , Zehra Aydın , Mihriban İnözü , Begüm Avcı , Fatma Şemsa Çaycı , Umut Selda Bayrakçı

https://doi.org/10.12956/tchd.1036384

Cited By: 1

Abstract

Objective: Fractional excretion of sodium (FeNa) and fractional excretion of urea (FeU) are used to differentiate prerenal and renal injuries in acute kidney injury (AKI). In this study, we aimed to compare the discriminative power of FeU with FeNa between prerenal and renal azotemia groups as well as among AKI stages according to pRIFLE criteria.

Material and Methods: Laboratory and medical records of 55 pediatric AKI patients who had the measurements of random urine excretions of urea, creatinine and sodium as well as serum urea, creatinine and sodium levels in order to calculate FeU and FeNa values at the time of AKI diagnosis were evaluated retrospectively. Patients were divided into prerenal and renal injury groups according to the clinical findings and laboratory data. Sensitivities and specifities of FeNa and FeU in differentiating prerenal versus renal injury were determined. FeNa and FeU values were compared in patients with different RIFLE stages.

Results: Among 55 pediatric AKI patients 31 were boys, 24 were girls. The mean age at the time of diagnosis was 71.1 ± 83.5 months (min-max: 1-216). When we grouped the patients as having FeU<35% and FeU≥35%, the difference between the numbers of the patients in prerenal and renal groups was significant (p=0.039). The sensitivity and specificity of FeU to determine prerenal vs renal injury were calculated as 50% and 77.1% respectively. When FeNa and FeU were used together (FeNa>1% and FeU>35%) in order to distinguish prerenal and renal injuries the specificity increased to 81% (p=0.020). Mean FeU was significantly different between AKI stages (p=0.022), and was higher in Injury and Failure stages when compared with the Risk stage.

Conclusion: Fractional urea excretion is as important as FeNa in evaluating children with AKI. We recommend to obtain FeU in pediatric AKI in order to differentiate prerenal and renal etiology and to differentiate the severity of the injury according to the AKI stages in order to arrange the treatment.

Keywords

Acute kidney injury, Children, Fractional urea excretion, pRIFLE

Pediatrik Akut Böbrek Hasarında Fraksiyone Üre Ekskresyonu

Abstract

Amaç: Fraksiyone sodyum ekskresyonu (FeNa) ile fraksiyone üre ekskresyonu (FeU) akut böbrek hasarında prerenal ve renal hasarı ayırt etmek için kullanılmaktadır. Bu çalışmada, FeNa ve FeU değerlerinin prerenal ve renal azotemi grupları ile pRIFLE kriterlerine göre akut böbek hasarı evrelerini ayırdetmedeki gücünü kıyaslamayı amaçladık.

Gereç ve Yöntemler: Akut böbrek hasarı tanısı sırasındaki FeU ve FeNa değerlerini hesaplamak amacıyla spot idrar üre, kreatinin ve sodyum ekskresyonları ile serum üre, kreatinin ve sodyum değerleri elde olunan 55 pediatrik akut böbrek hasarı hastasının laboratuvar ve klinik verileri retrospektif olarak değerlendirildi. Hastalar klinik ve laboratuvar bilgiler ışığında prerenal ve renal hasar grupları olarak ikiye ayrıldı. Prerenal ve renal hasarı ayırt etmede FeNa ve FeU testlerinin sensitivite ve spesifisiteleri hesaplandı. Farklı RIFLE evreleri olan hastalar arasında FeNa ve FeU yüzdeleri kıyaslandı.

Bulgular: Elli beş pediatrik akut böbrek hasarı hastasının 31’i erkek, 24’ü kızdı. Tanı anında ortalama yaş 71.1±83.5 ay (min-max: 1-216)’di. Hastaları FeU değerlerine göre FeU<%35 ve FeU ≥35% olarak iki gruba ayırdığımızda prerenal ve renal gruplardaki hasta sayıları arasındaki fark anlamlıydı (p=0.039). Prerenal ve renal hasar ayırımını belirlemede FeU testinin sensitivitesi %50, spesifisitesi %77.1 olarak hesaplandı. FeNa ve FeU birlikte kullanıldığında (FeNa >%1 ve FeU >%35) spesifisite %81’e yükseldi (p=0.020). FeU ortalaması akut böbrek hasarı evreleri arasında anlamlı olarak farklıydı (p=0.022) ve Risk evresiyle kıyaslandığında Injury ve Failure evrelerinde daha yüksekti.

Sonuç: Fraksiyone üre ekskresyonu, pediatrik akut böbrek hasarı olan çocukların değerlendirilmesinde FeNa kadar önemlidir. Prerenal ve renal hasarı ayırt etmede ve akut böbrek hasarı evrelerine göre böbrek hasarının şiddetinin belirlenmesinde FeU değerinin elde edilmesini öneriyoruz.

Keywords

Akut böbrek hasarı, fraksiyone üre ekskresyonu, pRIFLE

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