Transtubular potassium gradient (TTKG)

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 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).