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Pediatric Nephrology

, Volume 31, Issue 8, pp 1349–1353 | Cite as

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

  • Hisayo Fujita
  • Masayoshi Shinjoh
  • Tomohiro Ishii
  • Midori Awazu
Original Article

Abstract

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.

Keywords

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

Notes

Compliance with ethical standards

The ethics committee at Keio University School of Medicine approved this study. Parental consents were not obtained but the option of opting out was provided.

Disclosure

The authors declare that there is no conflict of interest to disclose.

References

  1. 1.
    Espinel CH (1976) The FENa test. Use in the differential diagnosis of acute renal failure. JAMA 236:579–581CrossRefPubMedGoogle Scholar
  2. 2.
    Zarich S, Fang LS, Diamond JR (1985) Fractional excretion of sodium. Exceptions to its diagnostic value. Arch Intern Med 145:108–112CrossRefPubMedGoogle Scholar
  3. 3.
    Diskin CJ, Stokes TJ, Dansby LM, Radcliff L, Carter TB (2010) Toward the optimal clinical use of the fraction excretion of solutes in oliguric azotemia. Ren Fail 32:1245–1254CrossRefPubMedGoogle Scholar
  4. 4.
    Kaplan AA, Kohn OF (1992) Fractional excretion of urea as a guide to renal dysfunction. Am J Nephrol 12:49–54CrossRefPubMedGoogle Scholar
  5. 5.
    Carvounis CP, Nisar S, Guro-Razuman S (2002) Significance of the fractional excretion of urea in the differential diagnosis of acute renal failure. Kidney Int 62:2223–2229CrossRefPubMedGoogle Scholar
  6. 6.
    Fahimi D, Mohajeri S, Hajizadeh N, Madani A, Esfahani ST, Ataei N, Mohsseni P, Honarmand M (2009) Comparison between fractional excretions of urea and sodium in children with acute kidney injury. Pediatr Nephrol 24:2409–2412CrossRefPubMedGoogle Scholar
  7. 7.
    Morgan DB, Carver ME, Payne RB (1977) Plasma creatinine and urea: creatinine ratio in patients with raised plasma urea. Br Med J 2:929–932CrossRefPubMedPubMedCentralGoogle Scholar
  8. 8.
    Kidney Disease: Improving Global Outcomes (KDIGO) Acute Kidney Injury Work Group (2012) KDIGO clinical practice guideline for acute kidney injury. Kidney Int Suppl 2:1–138CrossRefGoogle Scholar
  9. 9.
    Pepin MN, Bouchard J, Legault L, Ethier J (2007) Diagnostic performance of fractional excretion of urea and fractional excretion of sodium in the evaluations of patients with acute kidney injury with or without diuretic treatment. Am J Kidney Dis 50:566–573CrossRefPubMedGoogle Scholar
  10. 10.
    Diskin CJ, Stokes TJ, Dansby LM, Radcliff L, Carter TB (2010) The comparative benefits of the fractional excretion of urea and sodium in various azotemic oliguric states. Nephron Clin Pract 114:c145–150CrossRefPubMedGoogle Scholar
  11. 11.
    Quigley R, Lisec A, Baum M (2001) Ontogeny of rabbit proximal tubule urea permeability. Am J Physiol Regul Integr Comp Physiol 280:R1713–1718PubMedPubMedCentralGoogle Scholar

Copyright information

© IPNA 2016

Authors and Affiliations

  • Hisayo Fujita
    • 1
  • Masayoshi Shinjoh
    • 2
  • Tomohiro Ishii
    • 2
  • Midori Awazu
    • 2
  1. 1.Department of PediatricsHiratsuka Kyosai HospitalKanagawaJapan
  2. 2.Department of PediatricsKeio University School of MedicineShinjuku-ku, TokyoJapan

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