title: Inferior petrosal sinus ACTH and prolactin responses to CRH in ACTH-dependent Cushing's syndrome: a single centre experience from the United Kingdom.
abstract: Inferior petrosal sinus sampling (IPSS) of ACTH with CRH stimulation helps distinguish pituitary ACTH-dependent Cushing's syndrome from the ectopic ACTH syndrome (EAS). The usefulness of the paradoxical response of other pituitary hormones including prolactin to CRH remains controversial. Data from 33 IPSS procedures carried out at the Walton Centre for Neurology and Neurosurgery in Liverpool were analyzed. Patients were selected for this procedure if they had been diagnosed with ACTH dependent Cushing's syndrome and the majority had no obvious pituitary adenoma on Magnetic Resonance Imaging. Satisfactory simultaneous bilateral catheterization was accomplished in 23/33 (success rate 70%). The diagnostic sensitivity of a basal central/peripheral ACTH ratio >2.0 and >3 post-CRH was 94%. In two patients with subsequently confirmed EAS the maximal central/peripheral ACTH ratio was <2.0 on basal samples and did not change following CRH. The maximal central/peripheral prolactin ratio was noted at 5 min post-CRH, coinciding with the maximal central/peripheral ACTH ratio. The intersinus gradient (ISG) of ACTH was paralleled by a consistent ISG of prolactin and in 7 out of 9 patients (with successful bilateral IPSS and unilateral adenomas) the ISG of prolactin correctly lateralized the microadenoma whereas the ISG of ACTH correctly lateralized in 8 out of 9 patients. Neither of the patients with EAS achieved a central/peripheral prolactin ratio >2 in the basal state and >3 post-CRH. Bilateral catheterization of inferior petrosal sinuses can be successful in up to 70% of cases. Prolactin measurements do not have superior lateralizing capability compared with ACTH but may be useful in the differential diagnosis of pituitary-driven from EAS.
authors.affiliation: Diabetes & Endocrinology Clinical Research Group, Department of Endocrinology and Diabetes, Clinical Sciences Center, University Hospital Aintree, Lower Lane, Liverpool, UK. cdaousi@liverpool.ac.uk
authors.forename: Christina
authors.initials: C
authors.lastname: Daousi
authors.forename: Thomas
authors.initials: T
authors.lastname: Nixon
authors.forename: Mohsen
authors.initials: M
authors.lastname: Javadpour
authors.forename: Katharine
authors.initials: K
authors.lastname: Hayden
authors.forename: Ian A
authors.initials: IA
authors.lastname: MacFarlane
mesh_terms: D000182:ACTH Syndrome, Ectopic / Q000175:diagnosis / Q000378:metabolism*; D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000328:Adult; D003346:Corticotropin-Releasing Hormone / Q000494:pharmacology*; D003480:Cushing Syndrome / Q000175:diagnosis / Q000378:metabolism*; D005260:Female; D006728:Hormones / Q000494:pharmacology*; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D017591:Petrosal Sinus Sampling; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism*; D011863:Radioimmunoassay; D006113:United Kingdom; D055815:Young Adult
chemical_list: D006728:Hormones; D000324:Adrenocorticotropic Hormone; D011388:Prolactin; D003346:Corticotropin-Releasing Hormone