Enhanced Na+/H+ exchange in Cushing's syndrome reflects functional hypermineralocorticoidism.

Background: Patients with Cushing's syndrome exhibit a bimodal distribution of maximal rates of the erythrocyte amiloride-sensitive Na+/H+ exchange (NHE). Enhanced erythrocyte NHE has recently been found in patients with primary aldosteronism.

Objective: To test the hypothesis that occult hypermineralocorticoidism in a subset of patients with Cushing's syndrome is responsible for the greater than normal NHE.