What do trans-tubular potassium gradient (TKKG) measurements indicate in hyperkalemia (high serum potassium level)?

Updated: Apr 09, 2020
  • Author: Eleanor Lederer, MD, FASN; Chief Editor: Vecihi Batuman, MD, FASN  more...
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A TTKG of less than 3 suggests a lack of aldosterone effect on the collecting tubules (that is, the kidneys are not excreting potassium appropriately). A TTKG greater than 7 suggests an aldosterone effect, which would be appropriate in the setting of hyperkalemia. In pediatric patients with hyperkalemia, a TTKG greater than 10 is consistent with normal renal excretion of potassium; a TTKG of less than 8 implies inadequate potassium excretion, which is usually secondary to aldosterone deficiency or unresponsiveness. Checking a serum aldosterone level may be helpful.

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