Efficacy of Using Basal Plasma Adrenocorticotropic Hormone-radioimmunoassay (ACTH-RIA) Level in the Identification of the Cause of Cushing's Syndrome
SUTIN SRIUSSADAPORN, M.D.*, THAVATCHAI PEERAPATDIT,M.D.*, SATHIT VANNASAENG,M.D.*, SIRIRAT PLOYBUTR, M.Sc.*, WANNEE NITIY AN ANT, M.D.*, APICHATI VICHAYANRAT, M.D.*
Affiliation : * Division of Endocrinology and Metabolism, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.
Abstract Basal (8.00 a.m.) plasma ACTH-radioimmunoassay (ACTH-RIA) levels were studied in 32 cases of endogenous Cushing's syndrome (17 Cushing's disease, 13 adrenocortical tumors, and 2 ectopic ACTH syndrome) and 11 normal volunteers. There were overlaps in the ranges of plasma ACTH-RIA levels among patients with Cushing's disease, adrenocortical tumors, and nor- mal volunteers but not ectopic ACTH syndrome. By using different plasma ACTH-RIA levels as cut-off points in differentiating ACTH-dependent from ACTH-independent Cushing's syndrome, the level of 30 pg/ml had the highest diagnostic efficacy with a 94.7 per cent sensitivity, a 84.6 per cent specificity and a 90.6 per cent diagnostic accuracy.
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