Published: 2017-03-28

A prospective study indicating that fractional excretion of sodium is a good marker for fluid loss

Mahesh M. G., Prasanna Kumar H. R., Srinath K. M., Ashok P., Shilpa Avarebeel


Background: Pre-renal failure, a reversible form of acute renal failure (ARF), accounts for 60-70% of all cases of ARF. To study the factors affecting fractional excretion of sodium (FENa) in patients with pre-renal failure.

Methods: The study involved patients with pre-renal failure, admitted in a multi-speciality hospital in south India for a period of two years. The demographic and clinical data were collected using a standard pro forma. The correlation between FENa and factors such as age, diabetes mellitus, fluid loss, fever, urine output and creatinine of pre-renal failure were statistically evaluated.

Results: The prospective study involved 24 patients diagnosed as pre-renal failure with a mean age of 52.75±18.78. The subjects included 14 males and 10 females, with a median FENa of 0.55 (0.10-0.90). A moderate negative correlation was observed between FENa and fluid loss in pre-renal failure patients (r -0.646, P=0.0007).

Conclusions: The level of FENa may assist in estimating fluid loss in patients with pre-renal failure.


Acute tubular necrosis, FENa, Pre-renal failure

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Hoste EAJ. Pre-renal acute kidney failure. In: Jorres A, Ronco C, eds. Management of acute kidney problems. New York: Springer; 2010:33.

Needham E. Management of Acute Renal Failure. Am Fam Physician. 2005;72(9):1739-46.

Schrier RW. Diagnostic value of urinary sodium, chloride, urea, and flow. J Am Soc Nephrol. 2011;22(9):1610-3.

Carvounis CP, Nisar S, Guro-Razuman S. Significance of the fractional excretion of urea in the differential diagnosis of acute renal failure. Kidney Int. 2002;62(6):2223-9.

Nanji AJ. Increased fractional excretion of sodium in prerenal azotemia: need for careful interpretation. Clin Chem. 1981;27(7):1314-5.

Yassin AR, Sherif HM, Mousa AY, Esmat A. Comparison between fractional excretion of sodium and fractional excretion of urea in differentiating prerenal from renal azotemia in circulatory shock. Egyptian J Critical Care Med. 2013;1(2):69-77.

Legrand M, Le Cam B, Perbet S, Roger C, Darmon M, Guerci P, et al. Urine sodium concentration to predict fluid responsiveness in oliguric ICU patients: a prospective multicenter observational study. Crit Care. 2016;20(1):165.

Nguyen MT, Maynard SE, Kimmel PL. Misapplications of commonly used kidney equations: renal physiology in practice. Clin J Am Soc Nephrol. 2009;4(3):528-34.

Macedo E, Mehta RL. Prerenal Failure: From Old Concepts to New Paradigms. Curr Opin Crit Care. 2009;15(6):467-73.

Lam M, Kaufman CE. Fractional excretion of sodium as a guide to volume depletion during recovery from acute renal failure. Am J Kidney Dis. 1985;6(1):18-21.

Demirjian S. Nally J. Acute Kidney Injury, 2010. Available at: http://