TTKG Calculator — Transtubular Potassium Gradient
Estimate the transtubular potassium gradient (TTKG) to judge whether the kidney is responding appropriately to a potassium disturbance.
When to use it
In hyperkalemia a TTKG below 7 suggests hypoaldosteronism or aldosterone resistance; in hypokalemia a TTKG above 4 suggests renal potassium wasting. Requires urine osmolality above plasma and urine sodium above 25 mmol/L to be valid.
Formula
TTKG = (urine potassium x plasma osmolality) / (plasma potassium x urine osmolality).
Category
Acid-Base & Electrolytes
References
- Choi MJ, Ziyadeh FN. The utility of the transtubular potassium gradient in the evaluation of hyperkalemia. J Am Soc Nephrol. 2008;19:424-426.
About NephroMind
This calculator is part of NephroMind, a free clinical decision-aid platform from the Arab Society of Nephrology and Renal Transplantation (ASNRT) — over 128 bedside nephrology calculators plus a renal drug-dosing database, coded by a practicing transplant nephrologist.