ADRENOCORTICAL RESPONSE TO THE 48-HOUR ACTH TEST IN MYXEDEMA AND HYPERTHYROIDISM*

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Abstract
The response of urinary 17-hydroxycorticosteroids (17-OH-CS) and 17-ketosteroids (17-KS) to the standard 48-hour intravenous ACTH test was investigated in 12 patients with hyper- thyroidism and in 9 with myxedema. Control values for urinary 17-OH-CS were low in myxedema and slightly elevated in hyperthyroidism. Control values for urinary 17-KS were low in both myxedema and hyperthyroidism. In hyperthyroidism, there was a normal response of urinary 17-OH-CS excretion on the first day of ACTH stimulation but no further increase on the second day. This indicates some degree of impairment of adrenocortical reserve. In myxedema, the patients could be classified into 2 categories. One group exhibited a subnormal urinary steroid response on both days of ACTH stimulation, whereas the other group showed a normal response on the first day but a supra-normal response on the second day; moreover the elevated urinary 17-OH-CS persisted on the day following cessation of ACTH. It is suggested that in hyperthyroidism the production of adrenocortical steroids is increased, although there may be a decreased reserve. In myxedema, the production of adrenocortical steroids appears to be reduced but the response to ACTH stimulation varies from below normal to above normal.