The Fractional Excretion of Sodium (FENa) determines if renal failure is due to pre-renal, intrinsic, or post-renal pathology.

Low fractional excretion indicates sodium retention by the kidney, suggesting pathophysiology extrinsic to the urinary system such as volume depletion or decrease in effective circulating volume (e.g. low output heart failure). Higher values can suggest sodium wasting due to acute tubular necrosis or other causes of intrinsic kidney failure.

2024年10月30日 · The fractional excretion of sodium (FENa) measures the percent of filtered sodium that is excreted in the urine. This calculation is used to help differentiate prerenal disease (decreased kidney perfusion) from acute tubular necrosis (ATN) as the cause of …

FENa has traditionally been considered as lacking validity in patients on diuretics. In this study, FENa (>1%) had a specificity of just 54% in detecting intrinsic kidney injury. However, it is important to note that an FENa of <1% may still provide value in patients on diuretics, as noted by the high negative predictive value of 82% in this ...

The FENa test is highly effective in diagnosing prerenal azotemia. A FENa value below 1% indicates that the kidneys are conserving sodium in response to reduced blood flow, which is consistent with prerenal azotemia. With a PPV of 90% and an NPV of 95%, the test is a critical tool for early and accurate diagnosis. Acute Tubular Necrosis (ATN)

FeNa is useful for the classification of AKI, as pre-renal failure volume depletion causes a maximal stimulus for salt retention and hence a low FeNa. In other clinical situations, however, defining any single cut-off value for FeNa is unhelpful for the diagnosis of tubular dysfunction.

FENa was 0.4% to 0.8%, considerably lower than FENa's measured in eight nonvolume-depleted patients in acute renal failure. Vigorous intravenous fluid therapy in this patient produced a prompt increase in urine volume and improvement in renal function.

2008年10月24日 · To evaluate the mechanisms for a low fractional excretion of Na (FENa ≤ 1.0) in acute renal failure (ARF) of a sustained nature, causes were determined independent of FENa in 41 patients without volume depletion, obstruction, vasculitis or glomerulonephritis.

2012年9月5日 · 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. It seems like the kidneys are exceptionally sodium avid, as we are told through medical school that a FENa above 2% is equivalent to vast tubular death and dysfunction.

2023年12月31日 · 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. There are no risks with providing the urine sample. There is little risk involved with having your blood taken.