ToolsCalculators
Transtubular Potassium Gradient (TTKG)
Assesses renal potassium handling in dyskalemia.
Transtubular Potassium Gradient (TTKG)
Urine potassium
mEq/L
Serum potassium
mEq/L
Urine osmolality
mOsm/kg
Serum osmolality
mOsm/kg
Complete the fields above to see the result.
When to use
- Distinguishing renal from extrarenal causes of hyper- or hypokalemia by estimating cortical collecting duct potassium secretion.
Formula
TTKG = (urine K x serum osmolality) / (serum K x urine osmolality).
Pearls and pitfalls
- Only valid when urine osmolality exceeds serum osmolality and urine sodium is >25 mEq/L.
- The validity of TTKG has been questioned; interpret alongside other measures.