TY - JOUR
T1 - Interpretation of the Fractional Excretion of Sodium in the Absence of Acute Kidney Injury
T2 - A Cross-Sectional Study
AU - Schreuder, Michiel F.
AU - Bökenkamp, Arend
AU - Van Wijk, Joanna A.E.
PY - 2017/7/1
Y1 - 2017/7/1
N2 - Background/Aims: The fractional excretion of sodium (FeNa) may be helpful in establishing the cause of acute renal failure. This study was performed to determine the influence of the glomerular filtration rate (GFR), sodium intake, and tubular function on FeNa in children without renal failure. Methods: In this single institute cross-sectional study, 24-h-urine collections from patients (4-18 years of age, GFR >60 mL/min/1.73 m2) were used when considered reliable, and analyzed to determine sodium excretion, creatinine clearance and FeNa. The influence of tubular function was studied in 5 patients with generalized tubular dysfunction. Results: Based on data from 761 patients, a multiple regression formula was designed based on GFR and sodium excretion that predicted over 80% of the variation in FeNa (R2 = 0.824, p < 0.001). Using this formula, the predicted FeNa was significantly lower than the measured FeNa in the children with tubular dysfunction. Conclusion: FeNa depends on GFR and sodium intake, and tubular function cannot be assessed without possessing adequate knowledge on all factors. Therefore, no normal range or cut-off value for FeNa to assess tubular function can be given, and doing so is a misapplication of this equation.
AB - Background/Aims: The fractional excretion of sodium (FeNa) may be helpful in establishing the cause of acute renal failure. This study was performed to determine the influence of the glomerular filtration rate (GFR), sodium intake, and tubular function on FeNa in children without renal failure. Methods: In this single institute cross-sectional study, 24-h-urine collections from patients (4-18 years of age, GFR >60 mL/min/1.73 m2) were used when considered reliable, and analyzed to determine sodium excretion, creatinine clearance and FeNa. The influence of tubular function was studied in 5 patients with generalized tubular dysfunction. Results: Based on data from 761 patients, a multiple regression formula was designed based on GFR and sodium excretion that predicted over 80% of the variation in FeNa (R2 = 0.824, p < 0.001). Using this formula, the predicted FeNa was significantly lower than the measured FeNa in the children with tubular dysfunction. Conclusion: FeNa depends on GFR and sodium intake, and tubular function cannot be assessed without possessing adequate knowledge on all factors. Therefore, no normal range or cut-off value for FeNa to assess tubular function can be given, and doing so is a misapplication of this equation.
KW - Fractional excretion of sodium
KW - Glomerular filtration rate
KW - Renal tubular function
KW - Sodium excretion
UR - http://www.scopus.com/inward/record.url?scp=85018466985&partnerID=8YFLogxK
U2 - 10.1159/000468547
DO - 10.1159/000468547
M3 - Article
C2 - 28391266
AN - SCOPUS:85018466985
VL - 136
SP - 221
EP - 225
JO - Nephron
JF - Nephron
SN - 1660-8151
IS - 3
ER -