Transtubular Potassium Gradient TTKG Calculator
- Urine Potassium
- Plasma Potassium
- Urine Osmolality
- Plasma Osmolality
- Transtubular Potassium Gradient TTKG Explanation and Clinical Context
TTKG is a physiologic estimate of potassium secretion in the cortical collecting duct and reflects the activity of aldosterone as well as distal tubular sodium delivery. It is calculated by the ratio of urine potassium concentration to plasma potassium concentration multiplied by the ratio of plasma osmolality to urine osmolality. A TTKG value above seven typically indicates appropriate renal potassium secretion often seen in hyperkalemia due to increased aldosterone activity or adequate distal sodium flow while a value below three suggests impaired potassium secretion which can be consistent with hypoaldosteronism adrenal insufficiency or states of reduced distal sodium delivery. This tool supports clinical decision making by helping differentiate renal causes of hyperkalemia from extrarenal causes and by providing a physiologic window into aldosterone function.
Reference:
Kamel KS Schreiber M Halperin ML. Renal potassium handling and its clinical implications. Clin J Am Soc Nephrol. 2010. Palmer BF. Regulation of potassium homeostasis. Clin J Am Soc Nephrol. 2015.
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