Notes

• The transtubular potassium gradient in the cortical collecting duct is an index reflecting conservation of potassium. A normal TTKG in normal subjects on normal diets is 8-9.

• With a potassium load the TTKG may rise to 11.

• In the face of Hyperkalemia, a low TTKG (< 7) may indicate hypoaldosteronism.

• Without other disease, hypokalemia should produce a TTKG < 3 (some authors say TTKG < 2.) The expected TTKG in hyperkalemia is > 10.

         Pull down to select a related equation and transfer values in common Osmolar Clearance     [ Urine_Osm, Serum_Osm ]  
 

References

1. West ML, Marsden PA, Richardson RM, et. al. New clinical approach to evaluate disorders of potassium excretion. Mineral Electrolyt Metab. 12:234,1986.
2. Ethier JH, Kamel KS, Magner PO, et. al. The transtubular potassium concentration in patients with hypokalemia and hyperkalemia. Am J Kidney Dis. 15:309,1990.