Cushing's Disease: The Relevance of a Combined Dexamethasone Desmopressin Test as a Component of Postoperative Hormonal Evaluation

Background. The risk of Cushing's disease (CD) recurring may persist for years, even after initially successful surgery. Objective. To prospectively assess the relevance of a combined dexamethasone desmopressin test (CDDT) as a component of postoperative hormonal evaluation, including the dynamics of ACTH and cortisol concentrations. Material and Methods. We included 28 patients after TSS for CD. Eighteen months after surgery the standard hormonal evaluation was performed, followed by a CDDT. Results. Fifteen patients (53.6%) were in remission whereas in 13 subjects (46.4%) hypercortisolemia was confirmed. Positive results of CDDT were observed in 12 noncured patients (92.3%) and in one subject in remission (6.7%). Negative results were obtained in 12 patients with remission (80%) and in one noncured patient (7.7%). With 2 patients in CD remission (13.3%) the test results were inconclusive. We confirmed a high compatibility between CDDT and standard hormonal assessment results (κ = 0.846; P < 0.001). Significant differences in ACTH and cortisol levels at each CDDT time point between the two studied subgroups were shown. Conclusions. A negative CDDT result can be regarded as one of the factors indicative of CD remission during follow-up. Additionally, CDDT can help distinguish persistent hypercortisolemia from naturally recurring adrenal function after TSS.