Characterization of the normal temporal pattern of plasma corticosteroid levels.

Abstract

ABSTRACT The present studies had 2 objectives: I. To delineate more precisely the time course of adrenal secretory activity in the normal human and patients with Cushing's syndrome, by measurement of plasma corticosteroid and ACTH levels half-hourly throughout the 24 hr cycle. II. To describe hitherto lacking clinically optimal and suitable conditions for determination and definition of the normal circadian pattern of plasma corticosteroid levels (CPOHCS). 1. I. Four control subjects with normal activity sleep and meal time patterns were studied: 3 were restudied during “constant feeding,” 1 was restudied during constant glucose administration and again under different dexamethasone regimens. CPOHCS consisted of 5–10 peaks in a given subject. Fifty to 75% of peaks occurred in a 9 hr period (midnight to 9:00 am) describing a gradual upward course with maximum plasma corticosteroid levels occurring 1/2–2 hr following awakening. A downward trend followed with other peaking activity occurring between 11:30 am...