Effects of activity of 11β-hydroxysteroid dehydrogenase type 2 on serum potassium levels in Cushing's syndrome patients

Abstract

To explore the effects of different forms of glucocorticoid excess on cortisol/cortisone ratio and to reveal the mechanisms of hypokalemia in Cushing's syndrome patients. The levels of urinary free cortisol (UFF) and urinary free cortisone (UFE) were determined in 6 adult patients with ectopia adrenocorticotropic hormone (ACTH) syndrome, 6 normal serum level of potassium adults with hypercortisolism due to adrenal tumor, 5 hypokalemic adults with hypercortisolism due to adrenal tumor and 6 healthy volunteers using high-performance liquid chromatography plus tandem mass spectrometry (LC-MS/MS). For 4 groups, the results of UFF+UFE were (2 787 ± 820), (689 ± 163), (697 ± 120) and (70 ± 27)µg/L and UFF/UFE ratio 2.98 ± 0.35, 1.03 ± 0.42, 2.24 ± 0.37 and 0.42 ± 0.20 respectively. The values of UFF+UFE had no statistical difference between normal and low levels of serum potassium adults with hypercortisolism. And the ratio of UFF/UFE of hypokalemic adults with hypercortisolism was significantly higher than that of normal serum level of potassium adults with hypercortisolism. It suggested that the deficiency of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD 2) was present in hypokalemic adults with hypercortisolism. Due to a deficiency of 11β-HSD2, active cortisol can not be transformed into inactive cortisone in some patients with ACTH-independent Cushing's syndrome.