title: Determination of urinary 18-hydroxycortisol by isocratic normal-phase high-performance liquid chromatography.
abstract: A method for the determination of urinary 18-hydroxycortisol by high-performance liquid chromatography is described. Urinary samples were first mixed with an internal standard, 18-hydroxyprednisolone. 18-Hydroxycortisol and 18-hydroxyprednisolone, extracted by a Bond Elut column, were dehydrated by 1% (w/v) p-toluenesulphonic acid to the 11,18-epoxides. The epoxides were separated into two distinct peaks on a Resolve Silica column with a mobile phase of chloroform-methanol (100:2.5, v/v). The detection wavelength was 248 nm. The urinary 18-hydroxycortisol concentration was calculated from peak-height ratio of 11,18-epoxycortisol to 11,18-epoxyprednisolone. The linearity of the ratio was satisfactory in the range 12.5-300 ng per injection of 11,18-epoxycortisol. A specific increase of urinary 18-hydroxycortisol in patients with primary aldosteronism was demonstrated.
authors.affiliation: Department of Laboratory Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Chiba
authors.forename: Y
authors.initials: Y
authors.lastname: Ito
authors.forename: K
authors.initials: K
authors.lastname: Matsuno
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
authors.forename: T
authors.initials: T
authors.lastname: Kurosawa
authors.forename: S
authors.initials: S
authors.lastname: Ikegawa
authors.forename: R
authors.initials: R
authors.lastname: Mahara
authors.forename: M
authors.initials: M
authors.lastname: Tohma
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000652:urine; D006929:Hyperaldosteronism / Q000652:urine; D015203:Reproducibility of Results
chemical_list: C033689:18-hydroxycortisol; D006854:Hydrocortisone