Radioimmunoassay of plasma and urine 6 beta-hydroxycortisol: levels in healthy adults and in hypercortisolemic states.

A reliable radioimmunoassay for plasma and urine 6 beta-hydroxycortisol after chromatography on Sephadex LH 20 column has been described and evaluated. The antiserum used was raised in the rabbit injected with 6 beta-hydroxycortisol-3(O-carboxymethyl)oxime-bovine serum albumin. In control subjects, urine 6 beta-hydroxycortisol levels ranged from 137 to 348 micrograms/24 h (mean +/- SD: 238 +/- 66) in adult males (n = 14) and from 80 to 432 micrograms/24 h (mean +/- SD: 210 +/- 93) in adult females (n = 15). In plasma, 6 beta-hydroxycortisol levels ranged from 0.53 to 3.13 ng/ml (mean +/- SD: 1.14 +/- 0.57) in adult males (n = 17) and from 0.53 to 2.69 ng/ml (mean +/- SD: 1.22 +/- 0.53) in adult females (n = 19). In patients with Cushing's syndrome high levels were found in urine as well as in plasma. Finally the higher concentrations of 6 beta-hydroxycortisol found in adrenal effluent in comparison with those of the peripheral vein blood has clearly demonstrated that 6 beta-hydroxycortisol is secreted by the adrenal besides its extra-adrenal formation from cortisol.