Corticosterone methyloxidase II activity during hemodialysis.

Plasma levels of aldosterone decrease during hypokalemic hemodialysis. Our study was performed to determine whether the changes in plasma aldosterone level observed during hemodialysis are modulated by changes in corticosterone methyloxidase II activity. We measured plasma levels of adrenal zona glomerulosa steroids, for example, aldosterone and 18-hydroxycorticosterone (18-OH-B), immediately before and after 4 hours of hemodialysis (n = 8). Plasma levels of steroids originating from the adrenal zona fasciculata, for example, cortisol, corticosterone, 18-hydroxy-11-deoxycorticosterone, and 11-deoxycorticosterone, were also measured. Dialysance rates of 18-OH-B, aldosterone, and cortisol were calculated (n = 8). Plasma levels of both aldosterone (P less than 0.05) and 18-OH-B (p less than 0.01) decreased during hemodialysis. The 18-OH-B/aldosterone plasma concentration ratios did not change significantly during hemodialysis. No significant changes in plasma levels of fasciculata steroids were observed during hemodialysis. Dialysance rates for aldosterone and 18-OH-B were similar (P not significant). The dialysance of cortisol was 10-fold lower than that of aldosterone (P less than 0.01) and 18-OH-B (P less than 0.01). The relative constancy of the 18-OH-B/aldosterone plasma concentration ratios indicates that corticosterone methyloxidase II activity is normal in patients with end-stage renal disease who are maintained by hemodialysis.