Serum cortisol and 11-deoxycortisol by liquid chromatography: Clinical studies and comparison with radioimmunoassay

Abstract

Described is a liquid-chromatographic procedure for separating and measuring cortisol and 11-deoxycortisol in serum. The authors quantitated these steroids in patients who were undergoing various tests of pituitary and (or) adrenal function and compared the results with those obtained by two radioimmunoassays done in two different laboratories. Results of 48 tests done in 37 functionally normal humans are presented. Cortisol values for sera collected in the morning as determined by liquid chromatography were (mean±SD) 134±54 μg/L. Serum cortisol concentrations increased from 136±65 to 321±80 μg/L 60 min after injecting synthetic corticotropin and increased from 107±46 to 242±31 μg/L after insulin-induced hypoglycemia. Serum cortisol decreased from 142±49 to 26±20 μg/L after oral administration of metyrapone, while 11-deoxycortisol increased from <10 to 210±53 μg/L. Serum cortisol measured <10 μg/L the morning after oral ingestion of dexamethasone. Results of the dynamic tests of adrenal function correlated well with previously reported studies. However, the cortisol values obtained by their technique were generally lower than those obtained by radioimmunoassay, possibly owing to lack of specificity of the latter methods used here for comparison. In contrast, values for 11-deoxycortisol were the same by both methods.