Fraction Excretion of Sodium

Specimen Required

Spot Urine and Clotted Blood

Fasting Required

Purpose of the Fraction Excretion of Sodium Test

FeNa may be ordered when a person has symptoms of acute kidney injury, such as decreased urine output, swelling, and electrolyte imbalances. It may also be ordered when a person has a medical condition that affects kidney function or when taking medications that can cause kidney damage.

When this Fraction Excretion of Sodium test is required

FeNa may be requested when a person has symptoms of acute kidney injury or when a healthcare provider suspects a kidney problem during an outpatient visit.

What the Fraction Excretion of Sodium Test Detects

FeNa measures the percentage of sodium filtered by the kidneys that is excreted in the urine. Normally, the kidneys filter and reabsorb sodium, but in acute kidney injury, this process may be disrupted, resulting in increased sodium excretion in the urine.

Preparation for the Fraction Excretion of Sodium Test

No special preparation is required for the test.

Sample Requirements

A urine sample and a blood sample are required for the test.

Additional Notes

FeNa is not a definitive diagnostic test and should be interpreted in the context of a person’s overall medical condition and other laboratory and imaging tests. Other factors, such as medication use and dehydration, can also affect FeNa values.

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