Evaluation of the DDAVP test in the diagnosis of Cushing's Disease

ObjectiveTo analyse the performance of the desmopressin (DDAVP) test in the diagnosis of Cushing's disease (CD). MethodsThis was a prospective cohort study of 124 patients with suspected hypercortisolism who were recruited from an outpatient endocrinology clinic and investigated for Cushing's syndrome (CS). The ACTH and cortisol responses to the DDAVP test were assessed to determine patient diagnosis and test the procedure's diagnostic accuracy. ResultsA total of 68 patients had CD, while 56 had suspected CS. According to ROC analysis, an ACTH peak of 718pg/ml (158pmol/l) following DDAVP administration was able to diagnose CD with a specificity of 946% and a sensitivity of 908%, a negative predictive value (NPV) of 899% and a positive predictive value (PPV) of 953%. An absolute ACTH increment 37pg/ml (81pmol/l) over baseline had a sensitivity of 880%, specificity of 964%, NPV of 870% and PPV of 953% in diagnosing CD. Only 2 of 56 cases without CD had an absolute ACTH increment 37pg/ml (81pmol/l) over baseline. The DDAVP test was superior to other clinical instruments in diagnosing CS. ConclusionsThe DDAVP test could be a useful additional tool to diagnose CD in patients with suspected CS.