title: Urinary free cortisol and cortisone determined by high performance liquid chromatography in the diagnosis of Cushing's syndrome.
abstract: To determine the efficacy of cortisol and its metabolite, cortisone, measured simultaneously by high performance liquid chromatography (HPLC) in the diagnosis of Cushing's syndrome, we retrospectively reviewed the histories of 29 surgically proven Cushing's syndrome patients (20 Cushing's disease, 5 ectopic ACTH syndrome, and 4 adrenal Cushing's syndrome) and 6 patients with exogenous Cushing's syndrome. These 35 patients had urinary free cortisol determined by both HPLC and competitive binding methods. The efficacy of the HPLC assay using cortisol alone was equivalent to that of the competitive binding assay; 22 of 29 (76%) patients had increased cortisol. Cortisone also aided in the diagnosis; 25 of 29 (86%) had increased cortisone. Twenty-seven of the 29 (93%) patients had either both cortisone and cortisol (n = 19) or at least 1 of the 2 (n = 8) increased. All 6 patients with exogenous Cushing's syndrome had suppressed urinary free cortisol, cortisone, and the presence of prednisone and prednisolone. In the competitive binding assay, all exogenous Cushing's patients had falsely increased cortisol results. In conclusion, urinary free cortisol plus cortisone determined simultaneously by HPLC added a new dimension to the diagnosis of Cushing's syndrome. It should be considered when exogenous Cushing's syndrome is suspected or when only one urinary cortisol test is allowed to be ordered.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic and Foundation, Rochester, Minnesota 55905, USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Lin
authors.forename: T J
authors.initials: TJ
authors.lastname: Wu
authors.forename: D A
authors.initials: DA
authors.lastname: Machacek
authors.forename: N S
authors.initials: NS
authors.lastname: Jiang
authors.forename: P C
authors.initials: PC
authors.lastname: Kao
mesh_terms: D000182:ACTH Syndrome, Ectopic / Q000652:urine; D000305:Adrenal Cortex Hormones / Q000009:adverse effects; D000310:Adrenal Gland Neoplasms; D000328:Adult; D000368:Aged; D001667:Binding, Competitive; D002851:Chromatography, High Pressure Liquid; D003348:Cortisone / Q000652:urine*; D003480:Cushing Syndrome / Q000175:diagnosis* / Q000209:etiology / Q000652:urine; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000652:urine; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012189:Retrospective Studies
chemical_list: D000305:Adrenal Cortex Hormones; D003348:Cortisone; D006854:Hydrocortisone