Diurnal rhythm in the plasma concentration of cortisol in paediatric patients with orthostatic dysregulation

A gas chromatographic/mass spectrometric method using stable isotopically labelled cortisol as an internal standard was employed to determine patterns of episodic secretion of cortisol in three normal subjects and four paediatric patients with orthostatic dysregulation. The measurement of the plasma cortisol level at frequent time intervals revealed how the daily secretory pattern of cortisol differs in these patients and normal subjects.