Interactive FENa (Fractional Excretion of Sodium) calculator. Requires the calculator gadget.
Usage: {{FENa Calculator}}
FENa — Fractional Excretion of Sodium
| Parameter
|
Value
|
| Serum Sodium (mEq/L)
|
|
| Serum Creatinine (mg/dL)
|
|
| Urine Sodium (mEq/L)
|
|
| Urine Creatinine (mg/dL)
|
|
| FENa (%)
|
%
|
| Interpretation (in setting of oliguria/AKI)
|
| <1%
|
Pre-renal azotemia — Kidneys are sodium-avid (hypoperfusion, hypovolemia, heart failure, cirrhosis). Consider volume resuscitation.
|
| >2%
|
Intrinsic renal disease — ATN, AIN, or glomerulonephritis. Kidneys unable to concentrate urine.
|
| 1–2%
|
Indeterminate — May be seen in early ATN or with mixed etiologies. Clinical correlation required.
|
| Important Caveats
|
- FENa is unreliable on diuretics — use FEUrea instead
- Low FENa (<1%) can be seen in contrast nephropathy, rhabdomyolysis, early obstruction
- Not validated in CKD patients
|
| References
|
- Espinel CH. The FENa test: use in the differential diagnosis of acute renal failure. JAMA. 1976;236:579-581. PMID 947239.
- Steiner RW. Interpreting the fractional excretion of sodium. Am J Med. 1984;77:699-702. PMID 6486145.
|
