- Results altered by Hyperkalemia Management.
- Obtain lab sample prior to intervention if possible.
- Do not delay treatment in emergent Hyperkalemia.
- Serum Potassium and Serum Osmolality.
- Spot urine for Urine Potassium and Urine Osmolality.
Formula of Transtubular Potassium Gradient (TTPG)：
- TTPG = (Urine K+ x Serum Osm)/(Serum K+ x Urine Osm)
... where K+ is potassium and Osm is Osmolality.
Interpretation of Fractional Excretion of Potassium：
- TTPG <6-8%:>
- TTPG). TTPG >6-8: Extrarenal cause of Hyperkalemia (May also be increased in Chronic Renal Failure).