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Fractional Excretion of Potassium
Aka: Fractional Excretion of Potassium, FEK
- See Also
- Potassium Homeostasis
- Serum Potassium
- Urine Potassium
- Hyperkalemia
- Hypokalemia
- Indications
- Hyperkalemia
- Precautions
- Results altered by Hyperkalemia Management
- Obtain lab sample prior to intervention if possible
- Do not delay treatment in emergent Hyperkalemia
- Labs
- Serum Potassium and Serum Creatinine
- Spot urine for Urine Potassium and Urine Creatinine
- Formula
- FEK = (Potassium Excretion x 100)/(total filtered load)
- Potassium (K+) Excretion = (Urine K++) / (Serum K++)
- Total Load = (Urine Creatinine) / (Serum Creatinine)
- FEK = (uK x sCr x 100) / (sK x uCr)
- Interpretation of Fractional Excretion of Potassium
- FEK <10%: Renal cause of Hyperkalemia
- FEK >10%: Extrarenal cause of Hyperkalemia
- May also be increased in Chronic Renal Failure