What does the FENa tell you?
The FENa is a measure of the extraction of sodium and water from the glomerular filtrate. It is the ratio of the sodium filtration rate to the overall glomerular filtration rate (GFR).
What is a normal FENa?
What is a normal FENa? In plain-speak, the FENa, or fractional excretion of sodium, is the amount of sodium excreted in the urine out of all the sodium filtered at the glomerulus.
How do you calculate sodium excretion rate?
IV. Calculation
- Sodium Excretion = (Urine Sodium) / (Serum Sodium)
- Total filtered Load = (Urine Creatinine) / (Serum Creatinine)
How is FEUrea calculated?
III. Calculation
- Fractional Excretion of Urea (FEUrea in percent) = (sCr * uUrea) / (sUrea x uCr) * 100.
- Where. sCr: Serum Creatinine. uCr: Urine Creatinine. sUrea: Serum Urea (Blood Urea Nitrogen) uUrea: Urine Urea.
What causes high FENa?
In people with chronic underlying kidney disease (such as chronic glomerulonephritis), a superimposed acute prerenal condition can result in an elevated value of FENa, which can mislead doctors to think that ATN has occurred.
How useful is FENa?
FENa could play a supportive role in the diagnosis of hepatorenal syndrome, a disorder that is characterized by oliguria, avid sodium reabsorption, urine Na <10 mEq/L, and FENa <1 percent [1]. When diuretics may still be active and the FENa is not low, the fractional excretion of urea (FEUrea) may be helpful.
What does a low FENa mean?
FENa of lower than 1% indicates decreased blood flow to the kidney. This can occur with kidney damage due to dehydration or heart failure. FENa higher than 1% suggests damage to the kidney itself.
What is a normal fractional excretion of sodium?
In most normal subjects, the fractional excretion of sodium is usually less than 1 percent but may be raised with an increase in salt intake. In acutely azotemic patients, a low fractional excretion of sodium usually indicates a prerenal process that is responsive to volume repletion.
How do you calculate Fe uric acid?
It is calculated by dividing the product of (urinary uric acid [mg/mL] x serum creatinine [mg/mL]) by the product of (serum uric acid [mg/mL] x urinary creatinine [mg/mL]) and multiplying the result by 100%.
What is normal BUN to creatinine ratio?
The ideal ratio of BUN to creatinine falls between 10-to-1 and 20-to-1. Having a ratio above this range could mean you may not be getting enough blood flow to your kidneys, and could have conditions such as congestive heart failure, dehydration, or gastrointestinal bleeding.
How do diuretics affect FENa?
Use of diuretics can cause the FeNa to be falsely elevated in a pre-renal state. In response, researchers evaluated the FeUrea, generally using a cutoff of less than 30% for pre-renal and greater than 30% for ATI. Urea is passively absorbed, and its urinary concentrations are regulated by volume status.
