Doctaverse
Renal

Transtubular Potassium Gradient (TTKG)

Estimates the driving force for potassium secretion in the cortical collecting duct — used to work up hyper- and hypokalaemia.

Scope: The TTKG model has been questioned (medullary urea recycling); many nephrologists now favour the urine K/creatinine ratio. Use as one data point only.

Inputs

FieldUnitNotes
Urine potassium mEq/L 0–200
Plasma potassium mEq/L 1–12
Urine osmolality mOsm/kg 50–1400
Plasma osmolality mOsm/kg 200–400

FAQ

What is the Transtubular Potassium Gradient (TTKG)?

Estimates the driving force for potassium secretion in the cortical collecting duct — used to work up hyper- and hypokalaemia.

What inputs does the Transtubular Potassium Gradient (TTKG) need?

Urine potassium (mEq/L), Plasma potassium (mEq/L), Urine osmolality (mOsm/kg), Plasma osmolality (mOsm/kg).

Are there any limitations?

The TTKG model has been questioned (medullary urea recycling); many nephrologists now favour the urine K/creatinine ratio. Use as one data point only.

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