Circadian rhythms in plasma cortisone and cortisol and the cortisone/cortisol ratio

We evaluated the circadian rhythms in the plasma concentrations of cortisol, cortisone and their free forms, and in the cortisone/cortisol ratios by means of reversed-phase high performance liquid chromatography in normal adult subjects. Plasma concentrations of cortisone, as well as cortisol, exhibited a circadian rhythm. The ratios of cortisone/cortisol remained almost constant during the waking hours of normal subjects. Changes in the cortisone/cortisol ratios previously reported in patients with various diseases exceeded the diurnal changes detected in the present study. Thus, the determination of the cortisone/cortisol ratio provides information that is useful in assessing the adrenal function of patients with various diseases.