title: Cortisol production rate determined by radio gas-chromatography.
abstract: We describe a ratio gas-chromatographic method for determination of cortisol production rate by measuring the isotope dilution of urinary cortisol metabolites. The method was calibrated by analyzing [3H]tetrahydrocortisol and [3H]tetrahydrocortisone of known specific activities. Results are reasonably well reproducible, the coefficients of variation ranging from 8-15% of allotetrahydrocortisol/tetrahydrocortisol and from 9-19% for tetrahydrocortisone. Correlation coefficients were 0.966 and 0.998 for tetrahydrocortisone and allotetrahydrocortisol/tetrahydrocortisol, respectively, when the method was compared with a method involving thin-layer chromatography and colorimetry. Only one chromatographic step is needed for both purification and quantitation, thus time and effort are saved.
mesh_terms: D002849:Chromatography, Gas; D002855:Chromatography, Thin Layer; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D013760:Tetrahydrocortisol / Q000652:urine; D013761:Tetrahydrocortisone / Q000652:urine
chemical_list: D013761:Tetrahydrocortisone; D013760:Tetrahydrocortisol; D006854:Hydrocortisone