Project plan background

Screening for and diagnosing (endogenous) Cushing’s syndrome can be challenging. Three types of tests are most frequently used for determining biochemical hypercortisolism: 24-hour urine cortisol, 1 mg dexamethasone suppression test and late-night salivary cortisol. Late-night salivary cortisol, which is non-invasive to collect and practical, can be measured in saliva together with cortisone levels using LC-MS/MS techniques. However, there are no clear cut-off values for these hormones measured using LC-MS/MS techniques yet. In this project we will determine optimal cut-off levels of salivary cortisol, cortisone and their ratio for diagnosing hypercortisolism.

Project plan hypothesis

Our hypothesis is that by examining the optimal cut-off values of salivary cortisol, cortisone and their ratio measured using LC-MS/MS in a population of patients with proven Cushing’s syndrome, we can improve the accuracy of screening for hypercortisolism.

Project plan research plan

We are retrospectively building a database with information on the results of the three common tests for hypercortisolism screening, indications for testing, relevant medical information and finally the true diagnosis based on follow-up and histology. Using this, we will identify patients with true Cushing’s syndrome and calculate cut-off values for cortisol/cortisone in saliva with optimal sensitivity and specificity. Furthermore, we will compare the three screening tests for hypercortisolism for diagnostic accuracy.

Project plan anticipated results

We will set appropriate cut-off values and aim to implement them in Dutch guidelines. We expect that these comprehensively researched and calculated cut-off values, will favor the late-night salivary cortisol/cortisone ratio, also given its preanalytical advantages, as the first diagnostic test for hypercortisolism.