Blood Levels of 17-Hydroxycorticosteroids Following the Administration of Adrenal Steroids and Their Relation to Levels of Circulating Leukocytes 1

occurrence of neutrophilia and lymphopenia following the administration of ACTH or adrenal cortical extracts to mice. In 1948 these findings were confirmed in man by Hills, Forsham and Finch (2), who noted, in addition, a pronounced fall in eosinophils. These changes in the blood have been used widely as an index of adrenal cortical activity. With the development of a method for the determination of 17-hydroxycorticosteroids in small quantities of blood or plasma (3) it has become possible to determine the relationship of the changes in blood steroid levels to the changes in leukocytes. In order to investigate this relationship, standard doses of various corticosteroids were administered to normal individuals and the alterations in blood 17-hydroxycorticosteroids and in leukocytes were observed at intervals thereafter.