6 beta-hydroxycortisol in serum and urine as determined by enzyme immunoassay on microtitre plates.

We modified our previous enzyme immunoassay (Clin Chim Acta 1986;157:267-76) for estimating 6 beta-hydroxycortisol (6 beta-OHF) to provide a more routine procedure for measuring it in urine and to increase sensitivity for its measurement in serum. Precision, analytical recovery, specificity, and detection limit are reported. 6 beta-OHF and 17-hydroxycorticosteroids in 24-h and 4-h (08:00-12:00 h) urine collections from healthy volunteers showed no significant day-to-day differences in excretion rate for either collection period. Mean values for 6 beta-OHF in serum of men, women, and women taking oral contraceptives showed no significant differences among these groups.