title: Bilateral inferior petrosal sinus sampling in the differential diagnosis of adrenocorticotropin-dependent Cushing's syndrome: a comparison with other diagnostic tests.
abstract: To compare bilateral inferior petrosal sinus sampling (IPSS) with high dose dexamethasone (HDD) and CRH testing (using recently proposed stringent response criteria) in the differential diagnosis of ACTH-dependent Cushing's syndrome, we reviewed 53 consecutive cases. The main analysis was limited to 45 cases with confirmed diagnosis: 44 with pituitary dependency, proven by confirmatory histology and/or significant biochemical improvement after pituitary surgery, and 1 with ectopic ACTH syndrome. After HDD (2 mg every 6 h for 48 h), 21 of the 44 pituitary cases met the stringent more than 90% suppression criterion. Twenty-three of the 44 pituitary cases also underwent CRH testing; 16 of 23 met a stringent response criterion of a more than 50% serum cortisol rise. For HDD and CRH testing combined, 8 of 23 fulfilled both stringent criteria, 10 of 23 had discordant results, and 5 of 23 failed to fulfil either of the stringent criteria for pituitary dependency. IPSS was performed in all 44 of the proven pituitary cases; 36 had petrosal/peripheral ACTH ratios of 2.0 or more without CRH stimulation. Thus, in patients with proven pituitary disease, stringent response criteria to HDD and CRH testing were fulfilled by only 48% and 70%, respectively. IPSS, which gave direct evidence of pituitary ACTH secretion in 82% of the cases, is therefore considered necessary in a significant proportion of cases.
authors.affiliation: Sir George E. Clark Metabolic Unit, Royal Victoria Hospital, Belfast, Northern Ireland.
authors.forename: M I
authors.initials: MI
authors.lastname: Wiggam
authors.forename: A P
authors.initials: AP
authors.lastname: Heaney
authors.forename: E M
authors.initials: EM
authors.lastname: McIlrath
authors.forename: D R
authors.initials: DR
authors.lastname: McCance
authors.forename: B
authors.initials: B
authors.lastname: Sheridan
authors.forename: D R
authors.initials: DR
authors.lastname: Hadden
authors.forename: A B
authors.initials: AB
authors.lastname: Atkinson
mesh_terms: D000293:Adolescent; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism*; D000328:Adult; D000368:Aged; D003346:Corticotropin-Releasing Hormone; D003480:Cushing Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D003907:Dexamethasone; D003937:Diagnosis, Differential; D005260:Female; D005938:Glucocorticoids; D006801:Humans; D008297:Male; D008875:Middle Aged; D017591:Petrosal Sinus Sampling; D012680:Sensitivity and Specificity
chemical_list: D005938:Glucocorticoids; D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone