title: Discrepancies in results of low-and high-dose dexamethasone suppression tests for diagnosing preclinical Cushing's syndrome.
abstract: According to the diagnostic criteria for adrenal preclinical Cushing's syndrome (PreCS) established by a group headed by the Ministry of Health, Labor and Welfare (MHLW), low- and high-dose dexamethasone suppression tests (DSTs) must be performed to prove autonomous cortisol secretion, i.e., > or =3 microg/dL serum cortisol following 1-mg DST administration, and > or =1 microg/dL serum cortisol following 8-mg DST administration. However, discrepancies have been documented in the results of low-and high-dose DSTs. We therefore investigated the validity of the DST for diagnosing PreCS by performing 1-mg and 8-mg DSTs in 39 patients with adrenal incidentaloma, but no characteristic Cushingoid symptoms. In about half of these patients (20/39, 51.3%), high-dose DST was positive but low-dose was negative, and one or more of the other abnormalities of hypothalamus-pituitary-adrenal axis dysfunction was seen in 75% of these patients. Furthermore, no significant difference in incidence of glucose intolerance and hypertension was noted in patients with positive high-dose DST and negative low-dose DST compared with patients with positive low- and high-dose DST. Under the current MHLW diagnostic criteria, patients with positive high-dose DST and negative low-dose DST are not diagnosed with PreCS, but some of these patients should be. Discrepancies in the results of low- and high-dose DSTs appear attributable to the current cutoff values, and further investigations are necessary to resolve these discrepancies.
authors.affiliation: Department of Internal Medicine, Division of Metabolism and Endocrinology, St. Marianna University School of Medicine, Kawasaki.
authors.forename: Takuyuki
authors.initials: T
authors.lastname: Katabami
authors.forename: Ryusei
authors.initials: R
authors.lastname: Obi
authors.forename: Naoko
authors.initials: N
authors.lastname: Shirai
authors.forename: Satoru
authors.initials: S
authors.lastname: Naito
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Saito
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000150:complications / Q000175:diagnosis; D000328:Adult; D000368:Aged; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage; D003480:Cushing Syndrome / Q000097:blood / Q000175:diagnosis* / Q000209:etiology; D003907:Dexamethasone / Q000008:administration & dosage; D003940:Diagnostic Techniques, Endocrine / Q000592:standards*; D042241:Early Diagnosis; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D033162:Incidental Findings; D008297:Male; D008875:Middle Aged; D010913:Pituitary-Adrenal System / Q000502:physiology; D015203:Reproducibility of Results
chemical_list: D000893:Anti-Inflammatory Agents; D003907:Dexamethasone; D006854:Hydrocortisone