Corticosteroid therapy in children with asthma. Hypophyseo-adrenocortical inhibition.

The function of the hypophyseo-adrenocortical system was investigated by the method described by Robinson, Mattingly, and Cope (1962), based on the principle that if the system is functionally normal the blood cortisol level, which is decreased in the course of corticosteroid therapy, returns to normal after steroid withdrawal. In a number of asthmatic children on steroid therapy the blood cortisol level was determined. Steroids were then stopped abruptly, and during the subsequent 7 days the blood cortisol level was determined on three occasions. On the 9th and 10th day, the reactivity of the adrenal cortex was determined following ACTH (Cortrophin-Z, Organon) 1-5 u./kg. intramuscularly on two successive days. This dose of ACTH is one that produces maximal stimulation. The blood cortisol level was determined on both days 4 hours after ACTH had been given, and the level was compared with that of the previous day. The blood cortisol level was always determined at 8 a.m. ACTH, when given, was administered at 8 a.m., in which event the blood cortisol level at noon was determined. At the time of blood sampling, the test subject was in a basal condition (fasting, bed-rest for the previous 12 hours). For the determination of plasma cortisol, a fluorescence method was used, somewhat modified from that described earlier (Steward, AlbertRecht, and Osman, 1961; De Moor, Osinski, Deckx, and Steeno, 1962; Mattingly, 1962). The following groups were examined: 1. 61 healthy children in whom the blood cortisol level was determined at 8 a.m. 2. 13 healthy children in whom the ACTH test was carried out. 3. 14 children with asthma, who had never been treated with steroids. In these patients the Robinson ACTH test was performed.