Salivary Cortisol Levels in True and Apparent Hypercortisolism

Abstract

Total plasma cortisol measurements may be misleading when there are variations in the plasma cortisol-binding protein capacity resulting from drugs, pregnancy or congenital alterations in cortisol-binding globulin (CBG). Salivary cortisol levels, which represent the free component of plasma cortisol, are less affected by alterations in protein binding and have been used in the investigation of hypothalamic-pituitary-adrenal disorders. This study compares these two indices of adrenal function in conditions of true hypercortisolism and spurious hypercortisolism (resulting from oral contraceptive medication or pregnancy). The circadian variation of cortisol in plasma and saliva was studied in six patients with unequivocal hypercortisolism and compared with normal volunteers. In the normal group, plasma and salivary cortisol levels taken at 0900 h were significantly higher than those taken at 2400 h. Patients with Cushing's syndrome failed to show a significant difference between plasma and salivary cortisol levels collected at 0900 and 2400 h. Five patients with pituitary-dependent Cushing's disease, one patient with an adrenal carcinoma causing Cushing's syndrome and seven normal subjects each received a dexamethasone suppression test using a continuous infusion of dexamethasone sodium phosphate at a rate of 1 mg/h. There was no significant difference in the half-life disappearance rate of endogenous cortisol in either plasma or saliva comparing grouped data from patients with pituitary-dependent Cushing's disease with that of normal subjects. Failure of suppression of both plasma and salivary cortisol levels was observed in the one patient with adrenal carcinoma during dexamethasone infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of Plasma, Salivary, and Urinary Cortisol Levels for Diagnosis of Cushing’s Syndrome

“…Salivary cortisol sampling is simple and less invasive, so this method may be more useful and less stressful than blood collection [12,13]. In our study, late-night plasma and salivary cortisol levels showed a positive correlation.…”

“…It exists in both free (active) and protein-bound forms in the blood, but only in a free form in saliva [11]. Evans et al first studied the feasibility of late-night salivary cortisol measurements for the clinical evaluation of endogenous hypercortisolism in the 1980s [12]. Since then, these measurements have been shown to offer high sensitivity and specificity in the diagnosis of Cushing's syndrome [13].…”

Evaluation of the diagnostic criteria for Cushing’s disease in Japan [Review]

“…It exists in both free (active) and protein-bound forms in the blood, but only in a free form in saliva [17]. Evans et al first studied the feasibility of late-night salivary cortisol measurements for the clinical evaluation of endogenous hypercortisolism in the 1980s [18]. Since then, these measurements have been shown to offer high sensitivity and specificity in the diagnosis of Cushing's syndrome [19].…”

“…Salivary cortisol sampling is simple and relatively noninvasive, so may be more useful and less stressful than blood collection [18,19]. Salivary collection is performed by placing a cotton pledget in the mouth and chewing for 1-2 min, in a recumbent position at 23:00 in Japan, whereas this is done at bedtime or between 23:00 and 24:00 in the United States.…”

“…The ability to detect pituitary ACTH-secreting adenoma might be improved by using a 3 Tesla magnet, although small non-functioning adenoma can also be detected with this technique. In some cases of EAS, 18 F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) would be helpful in detecting the localization [32].…”