Recent reports have reinforced the usefulness of salivary cortisol (SAF) in the evaluation of cortisol dynamics and in the diagnosis of Cushing syndrome. However, few data are available on the usefulness of SAF and salivary aldosterone (SAL) in response to corticotrophin (ACTH) stimulus. The aim of the authors’ study was to standardize the response of SAF and SAL to the intramuscular injection of 250 μg of synthetic human β1–24 ACTH in healthy patients. This test was performed in 21 healthy adult volunteers. Salivary samples were obtained in baseline conditions and during 30, 60, 90, and 120 minutes after ACTH administration. The results showed that all healthy volunteers achieved SAF and SAL concentrations of at least 40.0 nmol/L and 100.0 pmol/L, respectively, after the stimulus. The clinical usefulness of this test was confirmed when patients with known adrenal dysfunction were studied. In three patients with primary adrenal insufficiency, blunted SAF and SAL responses were obtained. Six patients with secondary adrenal insufficiency demonstrated subnormal or blunted SAF and normal SAL responses after ACTH stimulation.
From these data, the authors suggest that corticoadrenal reserve can be easily, noninvasively, and accurately investigated through the simultaneous measurement of salivary cortisol and aldosterone in response to corticotrophin. Salivary aldosterone was helpful in the differential diagnosis of adrenocortical hypofunction.