Salivary cortisol measurements worked as well as plasma measurements and better than urine glucocorticoid excretion. We concluded that bedtime salivary cortisol measurement is a practical and accurate screening test for the diagnosis of Cushing's syndrome.
Measuring midnight salivary cortisol is an easy and noninvasive means of diagnosing hypercortisolism. Its diagnostic accuracy is identical to, if not better than, that of previously described gold standards
salivary cortisol testing is "better than, that of previously described gold standards." This makes salivary cortisol testing the gold standard for assessing cortisol levels