The Fractional Excretion of Sodium (FENa) calculator is a useful tool for assessing kidney function, particularly in differentiating between prerenal and intrinsic renal causes of acute kidney injury. FENa is calculated using the concentrations of sodium and creatinine in both urine and serum. This calculator allows you to input these values and select the appropriate units for creatinine measurements, providing a quick and accurate FENa percentage.
FENa < 1%: This typically indicates a prerenal cause of acute kidney injury, where the kidneys are conserving sodium due to decreased blood flow or volume depletion. Common causes include dehydration, heart failure, or cirrhosis.
FENa 1-2%: This range can be seen in both prerenal and intrinsic renal conditions, and further clinical correlation is needed to determine the underlying cause.
FENa > 2%: This suggests an intrinsic renal cause of acute kidney injury, where the kidneys are unable to reabsorb sodium effectively. Common causes include acute tubular necrosis, interstitial nephritis, or glomerulonephritis.
