Correlation of Plasma Acth Concentration With Adrenocortical Response in Normal Human Subjects, Surgical Patients, and Patients With Cushing's Disease*

Abstract

The role of ACTH in various clinical disorders has been difficult to ascertain because the available assay methods have lacked the sensitivity necessary for valid quantitation of the hormone in the plasma of normal subjects (1-4). Even the method of Lipscomb and Nelson (5), the most sensitive practical bioassay procedure now available, usually requires the injection of at least 0.05 mU of ACTH per rat, if responses are to be elicited that will be statistically significant without the use of a prohibitive number of animals. It is usually impractical to inject more than 5 ml of crude human plasma into a single rat. Therefore, in order to be accurately measurable by this procedure, the concentration of ACTH in the plasma must be at least 0.05 mU per 5 ml, or 1 mU per 100 ml.Numerous studies indicate that normal plasma levels of ACTH are well below this concentration. Byr the adrenal ascorbic acid depletion assay method, Sydnor, Sayers, Brown, and Tyler (1) were unable to detect ACTH in plasma of normal subjects, even after attempting to extract the hormone with oxvcellulose in preparation for the bioassay. These workers concluded that blood ACTH concentrations of normal human subjects were less than 0.5 mU per 100 ml. Using a similar procedure, Fujita (3) estimated the normal level of ACTH to be about 1 mU per L, i.e., 0.1 mU per 100 ml. Cooper and Nelson (6) were able to detect ACTH in the plasma of only 3 of 10 patients before surgery, by a method that they

Circadian Rhythm of Plasma Aldosterone Concentration in Patients with Primary Aldosteronism

“…Similar circadian rhythms have also been described for ACTH (3) and plasma renin activity (4). The plasma aldosterone rhythm therefore might he causally related to one or both of these stimuli.…”

Radioimmunoassay of ACTH in plasma

“…The disagreements in values obtained from small numbers of subjects by different investigators may therefore be more apparent than real. However, the values obtained by Ney et al (31) at 6 a.m. average significantly lower than those obtained even later in the morning by other investigators using the same assay system (28); it is possible that the extraction of the large volumes of plasma by Ney et al (31) was not as efficient as that observed with smaller volumes (30).…”

Changes in Pig Cervical Mucus in Relation to the Oestrous Cycle

“…Further¬ more, the relationships with regard to both time of onset and duration of lh release (Niswender, Reichert & Zimmerman, 1970) (Fonzo, Mins & Nelson, 1967). In this context, the first evidence for peak occurrence was at 09.00 hours; a time associated with heightened adrenocorticosteroid secretion in other species (Diraimondo & Forsham, 1956;Ney, Shimizu, Nicholson, Island & Liddle, 1963). Further evidence for adrenal implication was found in the preliminary 218 N.B.…”