Utility of fractional excretion of urea in the differential diagnosis of acute kidney injury in children

Hisayo Fujita, Masayoshi Shinjoh, Tomohiro Ishii, Midori Awazu

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Introduction: The fractional excretion of sodium (FENa) has been used as an index for the differential diagnosis of acute tubular necrosis (ATN) and prerenal acute kidney injury (AKI). The reliability of this index, however, decreases with the use of the diuretic agent furosemide. The fractional excretion of urea nitrogen (FEUN) has been shown to be useful in such settings in adults. The objective of this study was to examine whether FEUN is also useful in these settings in children. Methods: We assessed 102 episodes of AKI in 74 children, classifying these into three groups based on history, physical examination, urine examination and subsequent clinical course: (1) prerenal AKI without furosemide (N = 37), (2) prerenal AKI with furosemide (N = 32) and (3) ATN (N = 33). Results: Of the 37 prerenal AKI episodes without furosemide, 35 showed low FENa of <1 %, with an overall average of 0.35 ± 0.11 %, whereas prerenal AKI with furosemide (1.63 ± 0.37 %) and ATN (8.76 ± 2.11 %) were associated with a higher FENa. FEUN in the clinical setting of prerenal AKI was lower than that in ATN (27.9 ± 2.1 vs. 51.6 ± 3.8 %, respectively) and, in contrast to FENa, not significantly different between the categories of prerenal AKI with and without furosemide (29.2 ± 3.1 vs. 25.1 ± 2.9, respectively). The sensitivity of FEUN <35 % was 75 % in prerenal AKI with furosemide, whereas that of FENa was 53 %. Conclusions: FEUN is useful in detecting prerenal AKI in children administered furosemide.

Original languageEnglish
Pages (from-to)1349-1353
Number of pages5
JournalPediatric Nephrology
Issue number8
Publication statusPublished - 2016 Aug 1


  • Acute kidney injury
  • Acute tubular necrosis
  • Blood urea nitrogen-to-creatinine ratio
  • Fractional excretion of sodium
  • Fractional excretion of urea
  • Furosemide

ASJC Scopus subject areas

  • Nephrology
  • Pediatrics, Perinatology, and Child Health


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