The estimation of 6 beta-hydroxycortisol in urine -- a comparison of two methods: high performance liquid...

In the present study two recently developed methods, a high performance liquid chromatography (HPLC) and a radioimmunoassay (RIA) for the estimation of 6 beta-hydroxycortisol in urine were compared. Both methods showed a very reliable intraassay variation of about 5.2 or 7.2% respectively. Using the baseline values of excretion during a 24-hour collecting period in human urine, and after induction of the liver microsomal enzyme system by different substances, both methods gave identical values. The HPLC-method still needs an extraction step at the beginning of the analytical procedure, while a direct measurement in the urine can be performed with the RIA. Furthermore, the RIA is not time consuming and is easy to perform. As the antiserum is highly specific there is no cross-reaction with other cortisol metabolites.