Responses of plasma adrenocortical steroids to low dose ACTH in normal subjects.
OBJECTIVE
The standard ACTH test in clinical use employs a pharmacological dose of ACTH which assesses the maximum secretory capacity of the adrenal cortex. We have investigated the responses of plasma adrenocortical steroids including cortisol, aldosterone and dehydroepiandrosterone (DHEA) to physiological doses of ACTH (ACTH 1-24, tetracosactide, Cortrosyn) and determined the minimal dose which induces a response equivalent to that induced by a pharmacological dose of ACTH.


METHODS
Rapid ACTH tests at various physiological (0-1, 0.5, 1 and 5 micrograms) and standard pharmacological (250 micrograms) intravenous doses.


METHODS
Seven healthy normal volunteers.


METHODS
Plasma cortisol, aldosterone and DHEA were measured. Peak value and the increment from basal value were used as indices of responses.


RESULTS
Each steroid responded to physiological doses of ACTH in a dose dependent manner. The minimum dose inducing an equivalent response to 250 micrograms ACTH was 0.5 micrograms for peak and incremental values in cortisol and DHEA, while that for aldosterone was 0.1 microgram. The time to peak for each steroid was delayed as the dose increased. Plasma aldosterone and DHEA peaked significantly earlier than plasma cortisol in 1-5 micrograms and 0.5-5-micrograms ACTH tests, respectively.


CONCLUSIONS
These results suggest that the sensitivity of secretion to physiological doses of ACTH in descending order is aldosterone > DHEA = cortisol. When peak and incremental values are used, sufficient doses of ACTH are 0.1 microgram for plasma aldosterone and 0.5 microgram for plasma cortisol and DHEA in the rapid ACTH test.
Daidoh
H
H
Third Department of Internal Medicine, Gifu University School of Medicine, Japan.
Morita
H
H
Mune
T
T
Murayama
M
M
Hanafusa
J
J
Ni
H
H
Shibata
H
H
Yasuda
K
K
D000305:Adrenal Cortex Hormones / Q000097:blood*; D000328:Adult; D000450:Aldosterone / Q000097:blood; D003366:Cosyntropin / Q000008:administration & dosage* / Q000494:pharmacology; D003687:Dehydroepiandrosterone / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D013997:Time Factors
D000305:Adrenal Cortex Hormones; D003366:Cosyntropin; D003687:Dehydroepiandrosterone; D000450:Aldosterone; D006854:Hydrocortisone