Transtubular Potassium Gradient (TTKG)
Transtubular potassium gradient = (urine K/plasma K)/(urine osm/plasma osm); assesses renal K handling.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Urine K
- 40 mEq/L
- Plasma K
- 3.0 mEq/L
- Urine osmolality
- 600 mOsm/kg
- Plasma osmolality
- 290 mOsm/kg
- Urine Na
- 40 mEq/L
Result: TTKG 6.4 (hypokalemia with renal potassium wasting).
The tool opens with these values already filled in. Replace them with your own.
What you enter
- Urine K
- Plasma K
- Urine osmolality
- Plasma osmolality
- Urine Na
How this is calculated
Halperin ML, Kamel KS. Potassium. Lancet. 1998;352(9122):135-140. Derivation: Ethier JH, Kamel KS, Magner PO, et al. Am J Kidney Dis. 1990;15(4):309-315. TTKG = (urine K / plasma K) / (urine osm / plasma osm); read it only when urine osm > plasma osm and urine Na > 25. Read the sources: Halperin 1998 (the review) ↗, Ethier 1990 (the derivation) ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.