TTKG Calculator

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Calculate Transtubular Potassium Gradient to evaluate renal potassium handling.

Urine & Serum Labs

Urine Potassium

mEq/L

Serum Potassium

mEq/L

Urine Osmolality

mOsm/kg

Serum Osmolality

mOsm/kg

Renal Assessment

TTKG Index4.83

Balanced Feedback

Renal K+ Gradient

Quick Interpretation

Hypokalemia + TTKG > 3Renal K+ Loss

Hyperkalemia + TTKG < 6Aldosterone Deficit/Resist

About this calculator

Overview

The Transtubular Potassium Gradient (TTKG) is a clinical index used to estimate the potassium concentration gradient between the urine at the end of the cortical collecting duct (CCD) and the peritubular capillaries. It helps determine if the kidneys are responding appropriately to potassium imbalances (hypokalemia or hyperkalemia).

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Pro Tips

Ensure and double-check that the urine and serum samples were collected at roughly the same time.
A low TTKG in hyperkalemia points toward a distal tubule problem rather than just high intake.
Measurement of plasma aldosterone and renin levels often follows an abnormal TTKG result.

Fun Facts

"In a healthy person with normal diet, the TTKG is typically between 8 and 9."
"In hyperkalemia, a low TTKG (< 6) suggests a lack of aldosterone (e.g., Addison's disease) or aldosterone resistance."
"In hypokalemia, a high TTKG (> 3) suggests renal potassium wasting (e.g., hyperaldosteronism, diuretics)."
"The TTKG is only valid if Urine Osm > Serum Osm and Urine Na > 25 mEq/L."

Formula: TTKG = (Urine K / Serum K) / (Urine Osm / Serum Osm).