FENa Calculator

Calculate the fractional excretion of sodium given the serum and urine sodium, and the serum and urine creatinine.

Input Urine Sodium (U_Na)
Input Urine Creatinine (U_Cr)
Input Plasma Sodium (P_Na)
Input Plasma Creatinine (P_Cr)



FE_Na =		%

To accurately interpret FENa, patients should not have recently received diuretics. FENa is greater than 1% and usually greater than 3% with acute tubular necrosis and severe obstruction of the urinary drainage of both kidneys. It is generally less than 1% in patients with acute glomerulonephritis, hepatorenal syndrome, and states of prerenal azotemia such as congestive heart failure or dehydration. FENa may also be less than 1% with acute partial urinary tract obstruction. -- Stein JH, ed. Internal Medicine, 4th edition. Mosby-Year Book. 1994.

The equation is:

FE_Na =	U_Na * P_Cr	x 100

	P_Na * U_Cr

Created: January 7, 2000
Revised: October 19, 2000