EBMcalc Medical Calculator

Fractional Excretion of Sodium (FENa)

Input

Urine Sodium

Sodium

Urine Creatinine

Creatinine

Result

Important: Inputs must be complete to perform calculation.

FE Na

Decimal Precision

Data action

Include literature references: Yes No

Notes

The FENa helps differentiate acute tubular necrosis from a prerenal state.
FENa >2 % usually indicates ATN.
FENa <1% usually indicates a prerenal state such as dehydration or other forms of prerenal azotemia.
FENa's between 1% and 2% may be seen with either ATN or prerenal state.

Equations used

FENa = (UrineSodium / Sodium) / (UrineCreatinine / Creatinine) * 100

References

Stein JH, ed. Internal Medicine. 4th edition. Mosby-Year Book. 1994. NLMN ID: 9309759

Associated Logical Observation Identifiers Names and Codes [LOINC]

Parameter	LOINC's and Suggested Units
Urine Sodium	2955-3 : mEq/L 35678-2 : mEq/L 2955-3 : mmol/L 35678-2 : mmol/L
Sodium	2951-2 : mmol/L 2947-0 : mEq/L 32340-2 : mEq/L 39791-9 : mEq/L
Urine Creatinine	35674-1 : mg/dL 2161-8 : mg/dL 14683-7 : mmol/L
Creatinine	2160-0 : mg/dL 38483-4 : mg/dL 14682-9 : mcmol/L 22726-4 : mcmol/L 59826-8 : mcmol/L
FE Na	49135-7 : %

This material contains content from LOINC (http://loinc.org). LOINC is copyright © 1995-2023, Regenstrief Institute, Inc. and the Logical Observation Identifiers Names and Codes (LOINC) Committee and is available at no cost under the license at http://loinc.org/license. LOINC® is a registered United States trademark of Regenstrief Institute, Inc.

Associated ICD10-CM codes

N17.2

Acute kidney failure with medullary necrosis

N19

Unspecified kidney failure

N25.9

Disorder resulting from impaired renal tubular function, unspecified

N17.9

Acute kidney failure, unspecified

Associated ICD9-CM codes

276.5

Hypovolemia

584.9

Acute renal failure nos

588.8

Impaired renal funct nec

588.9

Impaired renal funct nos

586

Renal failure nos

583.7

Nephr nos/medull necros

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