Background: Inferior petrosal sinus sampling (IPSS) is indicated in the diagnosis of adrenocor-ticotropic hormone (ACTH)-dependent Cushings syndrome (CS), especially when the results of the initial diagnostic tests are discordant.
Objective: To describe the patients who underwent this invasive functional test in a tertiary hospital.
Methods: This was an observational study of a retrospective cohort of patients with ACTH- dependent CS and IPSS between 2004 and 2022. We determined their epidemiological, hormonal, radiological and functional characteristics, and evaluated their diagnostic capacity and optimal cut-off points to differentiate between Cushings disease (CD) and ectopic Cushings syndrome (ECS).
Results: 31 patients were evaluated. It was observed an ACTH secretion of a pituitary origin in 80% of cases and an ectopic origin in 20%. Patients with CD were more frequent female (64%) and those with ECS were mostly male (83.3%). There were no differences between age of diagnosis. Plasma cortisol, urinary free cortisol, and ACTH levels were higher in patients with ECS. Most IPSS were done before going to a definitive surgical treatment, so only 12.9% IPSS were done after surgery, meaning that persistence or recurrence of hypercortisolisim was detected during follow-up. Regarding radiological findings, patients with IPSS gradient ACTH C/P compatible with CD (>2 basal or >3 after CRH stimulation) had a visible adenoma in 40% of cases, with a median size of 4 (2.55.0) mm. On the other hand, patients with a IPSS gradient of ECS had 33% cases of MRI positive, with a median adenoma size of 7 (7.07.0) mm.
Conclusion: ACTH-dependent CS can be a difficult entity to diagnose for clinicians. Clinical, biochemical and radiological characteristics of patients provide an approach to etiologic diagnosis but not in all cases. IPSS with CRH stimulation is a test with a high diagnostic accuracy and it is particularly recommended in patients with negative MRI or with adenoma smaller than 610 mm.
13 May 2023 - 16 May 2023