Clinical Studies on the Stimulation and Suppression in the Pituitary-Adrenocortical System
II. Studies on the suppression test of the pituitary-adrenocortical system
1968 Volume 44 Issue 9 Pages 1016-1024,969
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1968 Volume 44 Issue 9 Pages 1016-1024,969
In order to evaluate the usefulness of dexamethasone suppression test for the diagnosis of certain clinical disorders which show elevated urinary 17-OHCS excretion, the effects of small and large doses of dexamethasone on urinary 17-OHCS excretion were studied in normal subjects, patients with simple obesity, Cushing's syndrome and hyperthyroidism. Urinary 17-OHCS excretion was measured by means of a modification of the method of Reddy, Jenkins and Thorn. Dexamethasone was administered for 9 days in the following way : 1.0 mg. daily for 3 days, 2.0 mg. daily for 3 days and 8.0 mg. daily for 3 days, in 4 divided doses.
1) Urinary 17-OHCS excretion in 5 normal subjects and 7 patients with simple obesity was suppressed by a daily administration of 1.0 mg. of dexamethasone for 3 days. Urinary 17-OHCS was rather more markedly suppressed in patients with simple obesity than in normal subjects.
2) Urinary 17-OHCS excretion in 2 patients with Cushing's syndrome due to bilateral adrenocortical hyperplasia was not suppressed by the daily administration of 1.0 mg. of dexamethasone for 3 days. Therefore, Cushing's syndrome in patients can be clearly differentiated from normal subjects or patients with simple obesity by this test. Urinary 17-OHCS excretion was occasionally suppressed in patients with Cushing's syndrome by the daily administration of 2.0 mg. of dexamethasone for 3 days. It seems to be pertinent, therefore, to administer 1.0 mg. of dexamethasone daily for the purpose of differentiating Cushing's syndrome from simple obesity.
3) Daily administration of 8.0 mg. of dexamethasone for 3 days did not suppress urinary 17-OHCS excretion in 3 patients with Cushing's syndrome due to adrenocortical adenoma, but suppressed it to the level lower than 5.0 mg. /day in 2 patients with bilateral adrenocortical hyperplasia. Therefore, adrenocortical adenoma can be differentiated from bilateral adrenocortical hyperplasia in Cushing's syndrome by giving 8.0 mg. of dexamethasone for 3 days.
4) Suppressibility of the daily urinary 17-OHCS in 6 patients with hyperthyroidism was almost equal to that in normal subjects by the daily administration of 1.0 mg. of dexamethasone for 3 days, although the actual values of the daily urinary 17-OHCS were higher than those of normal subjects.
