Fractional Excretion of Sodium (FENa)

A FENa test is advised by a doctor when you have acute kidney injury (AKI), such as a sudden rise in creatinine or reduced urine output. It helps determine whether kidney dysfunction is due to dehydration or low blood flow (prerenal) or direct kidney damage, guiding fluid therapy and treatment, especially in hospitalized patients.

No fasting is required for a FENa test. It requires a blood sample and a spot urine sample collected at the same time. Ideally, give the samples before receiving diuretics or IV fluids, as these can affect results. Inform your doctor about any diuretics, recent contrast dye exposure, or other medicines you take.

No, fasting is not required for a FENa test. You can eat and drink normally before the test. However, the blood and urine samples must be collected at the same time, ideally before diuretics or IV fluids are given, because these can affect the accuracy of the results.