The aim of this study was to examine and compare the potential usefulness of plasma and salivary
6beta-hydroxycortisol measurements for assessing adrenocortical activity in patients with
adrenocortical adenomas. Plasma and salivary
cortisol as well as
6beta-hydroxycortisol determinations were performed by radioimmunoassay after extraction with
ethyl acetate followed by chromatographic separation using a modified paper chromatographic system. Samples were obtained from 36 control subjects and 37 patients with non-hyperfunctioning
adrenocortical adenomas in the morning at 8 a.m. after a low-dose of
dexamethasone and after stimulation with synthetic depot
ACTH. Basal and post-
dexamethasone hormone levels were also measured in plasma and salivary samples of 4 patients with
Cushing's syndrome from adrenal
adenomas. In the baseline state, patients with non-hyperfunctioning
adrenocortical adenomas had significantly higher plasma and salivary
6beta-hydroxycortisol levels (mean+/-SE, 79.0+/-7 and 17.1+/-2.2 ng/dl, respectively) compared to those measured in controls (62.0+/-4 and 7.7+/-0.6 ng/dl, respectively), whereas baseline plasma and salivary
cortisol levels (9.6+/-0.5 microg/dl and 342+/-39 ng/dl, respectively) were similar to those measured in the control group (9.9+/-0.4 microg/dl and 366+/-24 ng/dl, respectively). In all groups, the changes in plasma and salivary
6beta-hydroxycortisol concentrations after
dexamethasone suppression and
ACTH stimulation were similar to the changes in plasma and salivary
cortisol levels, although the differing ratios of 6betaOHF to
cortisol indicated potentially important variations in the induction of 6beta-hydroxylase activity between the three groups. In patients with
Cushing's syndrome, baseline plasma and salivary
6beta-hydroxycortisol concentrations (754+/-444 and 104+/-88 ng/dl, respectively) were more markedly increased than plasma and salivary
cortisol levels (24.8+/-6.7 microg/dl and 1100+/-184 ng/dl, respectively), and all remained non-suppressible after
dexamethasone administration. These results suggests that plasma and salivary
6beta-hydroxycortisol determinations may precisely detect not only overt increases of
cortisol secretion in patients with
Cushing's syndrome but also mild
glucocorticoid overproduction presumably present in patients with non-hyperfunctioning adrenocortical
tumors.