The role of bilateral inferior petrosal sinus sampling in the diagnosis of Cushing's syndrome

Abstract

Adrenocorticotropin hormone (ACTH)-dependent Cushing's syndrome is most often due to a pituitary corticotroph adenoma, with ectopic ACTH-secreting tumors representing approximately 15% of cases. Biochemical and radiological techniques have been established to help distinguish between these two entities, and thus aid in the localization of the neoplastic lesion for surgical resection. The test that offers the highest sensitivity and specificity is bilateral inferior petrosal sinus sampling (BIPSS). BIPSS is an interventional radiology procedure in which ACTH levels obtained from venous drainage very near the pituitary gland are compared to peripheral blood levels before and after corticotropin hormone (CRH) stimulation. A gradient between these two locations indicates pituitary Cushing's, whereas the absence of a gradient suggests ectopic Cushing's. Accurate BIPSS results require hypercortisolemia to suppress normal corticotroph ACTH production and hypercortisolemia at the time of the BIPSS to assure excessive ACTH secretion. In some cases, intrapituitary gradients from side-to-side can be helpful to localize small corticotroph adenomas within the sella. BIPSS has rare complications and is considered safe when performed at centers with experience in this specialized technique.

Inferior petrosal sinus sampling: Final solution to a riddle called “Cushing's syndrome”

“…5 It is associated with marked morbidity and mortality thus its definitive treatment is mandatory which requires localization of ACTH source to pituitary. 6 Cushing's disease is caused by microadenomas (<1 cm) in more than 90% of cases. In only 36e78% of cases MRI is able to localize the adenoma in pituitary because of very small sized adenoma or diffuse corticotroph hyperplasia.…”

Recommendations of the Neuroendocrinology Department of the Brazilian Society of Endocrinology and Metabolism for the diagnosis of Cushing’s disease in Brazil

“…Fortunately, false positives are rare and can occur in cases of EAS during periods of normocortisolism (cyclical Cushing's syndrome or use of medical therapy for Cushing's) or in the rare case of ectopic CRH secretion (146).…”

“…Several aspects have to be observed during the procedure to ensure a reliable collection, including the following: successful catheterization, as confirmed by visualization of the intercavernous sinuses and contralateral petrosal sinus after contrast infusion; observation of anomalies or asymmetries in the petrosal sinus drainage (123,146,158); and proper processing of the samples collected by storage in previously chilled plastic tubes with EDTA and immediate placement in an ice bath after collection.…”

Aspectos técnicos e funcionais da cateterização dos seios petrosos inferiores na síndrome de Cushing ACTH dependente

“…Após a confirmação da hipercortisolemia e da possível dependência do hormônio adrenocorticotrófico (ACTH), a origem da produção do ACTH deve ser determinada (1). As principais causas de síndrome de Cushing dependente de ACTH são os adenomas hipofisários, que, de acordo com estudo epidemiológi-co europeu recente, correspondem a mais de 60% dos casos.…”

“…A presença de níveis elevados de ACTH na circulação sistêmica não fornece informações a respeito do local da produção deste (1). Com o intuito de localizar a origem da produção de ACTH, a sequência diagnós-tica inclui, além dos testes de supressão hormonal, a realização de ressonância nuclear magnética (RNM) de hipófise (3).…”