ECE2015 Guided Posters Pituitary – Diagnosis of Cushing's disease (6 abstracts)
Bilateral inferior petrosal sinus sampling reliably differentiates pituitary from ectopic Cushing's, but frequently fails to predict pituitary tumour location, especially when lateralizing to the right
Olympia Koulouri 1, , Nishita Nigam 1 , Andrew Powlson 1, , Neil Donnelly 2 , Richard Mannion 2 , John Pickard 1, , Brendan Koo 2 , David Halsall 1, & Mark Gurnell 1,
1University of Cambridge, Cambridge, UK; 2Addenbrooke’s hospital, Cambridge, UK.
Background: BIPSS remains the gold standard for differentiating pituitary and ectopic sources in ACTH-dependent Cushing’s syndrome. A pituitary:peripheral ACTH ratio >2 in the basal state, and/or >3 following CRH stimulation, is considered indicative of pituitary Cushing’s, with a range of sensitivities and specificities cited in the literature. In addition, in Cushing’s disease a peak interpetrosal gradient of >1.4 has been reported to predict the site of the adenoma in approximately 2/3 of cases. We examined the performance of BIPSS against these criteria in a cohort of patients who had undergone the procedure in our centre over the last decade.
Methods: 39 patients with biochemically proven ACTH-dependent Cushing’s, who had undergone BIPSS and had either subsequent histological confirmation of the ACTH source, or significant improvement/cure of their Cushing’s following transsphenoidal surgery, were included in the study.
Results: Based on basal ACTH levels (pre-CRH stimulation), 89% of patients were deemed to have pituitary Cushing’s and 11% an ectopic source. Post-CRH stimulation 94% of patients reached the cut-off for pituitary Cushing’s. This gave a sensitivity of 97% and a specificity of 100% for pre-CRH stimulation and 100% sensitivity and 67% specificity for post-CRH stimulation. Two thirds (65%) of BIPSS procedures exhibited lateralisation to the right side, but this was subsequently shown at surgery to be correct in only half of the patients. In contrast, left lateralisation had a much higher positive predictive value (80%). When combined, lateralisation (either right or left) was accurate in only 60% of cases.
Conclusions: Predominance of right sided lateralisation on BIPSS may signify a ‘dominant’ right sinus in many patients undergoing this procedure. We suggest therefore that whole gland exploration is particularly important in ‘right sided’ BIPSS cases, and additional pituitary imaging (e.g. volumetric MRI, functional imaging) may be helpful in informing the surgical approach.
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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