The function of the adrenal glands in the newborn.

It is well known that the adrenal cortex of the newborn infant differs anatomically from that of the adult and that morphological changes take place in the gland during the first few days and weeks of extra-uterine life. Until recent times, however, very little had been known about the function of the adrenal cortex during this period and it is questioned whether or not the adrenal, like the kidney, behaves differently from the adult gland at this time. Efforts have been made to study the problem by assaying the excretion of adrenal cortical metabolites in the urine of newlyborn infants and it has been shown that small quantities of such substances not only occur in the first few days of life (Venning, Randall and Gyorgy, 1949; Matson and Longwell, 1949) but also increase significantly in the second week (Read, Venning and Ripstein, 1950). Furthermore the reaction to stress as shown by the response to the administration of epinephrine suggests that the pituitary-adrenal axis is capable of normal function as early as the first day in full-term infants, although prematures do not show this response before the ninth day of life (Jailer, Wong and Engle, 1951). It was therefore considered worth while to study further this problem of adreno-cortical function in the newborn and, as a test of adreno-cortical stimulation, the eosinophil count in the peripheral blood and its response to A.C.T.H. was investigated. Using Thorn's (1948) test a fall in eosinophils of 50% or more below the pre-injection level indicates a satisfactory adreno-cortical response and in all probability eliminates the possibility of adrenocortical insufficiency. Although 25 mg. A.C.T.H. was described as a suitable test dose for adults, 5 mg. was arbitrarily chosen as an adequate stimulus for newborn infants. The eosinophil counts were made on capillary blood obtained by heel prick by the method of Randolph (1949) using the phlox ne propylene glycol stain. An attempt was made to carry out the second part of the test by estimating the uric acid/creatinine ratio in the urine before and after the injection of