SUN-462 Petrous Sinus Catheterization, Baseline and after Stimulation with Desmopressin, for the Diagnosis of Cushing's Disease, Experience of a National Health Institute in Mexico

Introduction: Cushing's disease (CD) is, in some cases, difficult to diagnose and the petrosal sinus catheterization (PSC) is indicated to rule out other etiologies of hypercortisolism, mainly in patients without a visible adenoma, that have an adenoma less than 6 mm or when the dynamic tests are discordant, and the suspicion of CD remains. Objective: To evaluate basal PSC and PSC after stimulation with desmopressin as a diagnostic tool for CD. As a secondary outcome we described the clinical and characteristics of the enrolled patients. Methods: We included all patients who underwent petrosal sinus catheterization since 1980 at our Institution and were >18 years old. We exclude all patients that underwent the procedure after surgical resection or radiotherapy of the adenoma for any reason. We eliminated patients that had incomplete information regarding the procedure. The gold standard for diagnosing CD was the histological evidence of an adenoma and/or remission of the disease with surgery. Results: We included 26 patients, 84.6% women, with an average age at diagnosis of 31 (23-40) years. The most common comorbidities were dyslipidemia (61.5%), followed by glucose abnormalities (50%). The main indication to perform the PSC was to have an adenoma smaller than 6 mm (38.4%). The final diagnosis was CD in 84.6% (n = 22) and adrenal hyperplasia in the rest (n = 4), there were no patients with ectopic Cushing's syndrome in our series. We couldn’t evaluate the usefulness of the procedure regarding the laterality of the adenoma because not all the patients had a complete report of the MRI. The central to peripheral gradient of ACTH (CPGA) > 1.2 (baseline), showed a sensitivity 95%, specificity 75%, positive predictive value (PPV) 95%, negative predictive value (NPV) 75%, positive likelihood ratio (LR+) 3.81 and negative likelihood ratio (LR-) 0.06. The CPGA post-stimulation with desmopressin > 2 had a sensitivity 86%, specificity 75%, PPV 95%, NPV 50%, LR+ 3.45, LR- 0.18. Conclusions: The PSC is a useful tool to make the differential diagnosis of CD with adrenal Cushing, when is indicated. The stimulation with desmopressin shows an adequate performance compared to that reported for CRH. A gradient > 1.2 baseline and > 2 post-stimulation can be used as diagnostic criteria.