The elucidation of adrenal-cortical status by measuring two-hour urinary-free cortisol levels

Urinary-free cortisol (UFC) measured in 24-h samples has provided unambiguous data regarding adrenal-cortical status, but collection is cumbersome and compliance is a problem. We reasoned that measuring UFC in 2-h samples collected at strategic times would distinguish patients with adrenal-cortical disorders from normal subjects. Patients with Cushing's syndrome demonstrated late P.M. (samples collected between 2000 and 2400 h) 2-h UFC levels that were greater than or equal to 12.0 micrograms/2 h (reference interval for this time period is 0.1-3.2 micrograms/2 h, n = 35). Several patients with various symptoms of Cushing's syndrome displayed late P.M. levels within the reference interval. Those with adrenal insufficiency had morning (collected between 0500 and 0900 h) levels less than or equal to 0.2 microgram/2 h (reference interval 1.7-21.2 micrograms/2 h, n = 37). These data indicate that adrenal-cortical status is reflected by measuring UFC levels in 2-h samples.