Persistence of a circadian rhythmicity of glucocorticoid secretion in a patient with Cushing's syndrome: study before and after unilateral adrenalectomy.

A 47-year-old woman affected by Cushing's syndrome due to an adrenal adenoma is described. An altered but rhythmometrically apparent cortisol secretory rhythm was detected using the single-cosinor computation. In fact serum cortisol levels and urinary excretion of 17-OHCS were elevated in the PM hours, particularly between 14:00-18.00 h and 18:00-22:00 h, and normal between 02:00-10:00 h. The patient was cured by unilateral adrenalectomy and one year later the circadian rhythm of corticosteroids secretion was investigated again. A normal rhythm of cortisol secretion and of 17-OHCS urinary excretion was found. Though it may be hypothesized that factors intrinsic to the tumoral adrenal cells were responsible for the rhythmic, but phase-shifted, hormonal release, the cause of the persistent and abnormal cortisol secretory rhythm is unknown.