The availability of D-phenylalanine and DL-phenylalanine
Abstract
nonsuppressors.had ACTH levels less than IS pg/ml; 17 of the 20 had ACTH levels less than 10 pg/ml and three had levels between 10 and 15 pg/ml. All 13 patients who were suppressors on the DST also had ACTH levels of less than IS pg/ml; I I had levels of less than 10 pg/mI and two had levels between 10 and 15 pg/ml. Of the nonsuppressors, two had levels less than 10 pg/mI, two had levels between 10 and 15 pg/mI, and five had levels greater than IS pg/mI. There was a highly significant difference between the ACTH values of the psychiatric patients who were suppressors and those who were nonsuppressors (6.5±2.3 and 19.9±10.9 pg/ml, Mann-Whitney U test, one-tailed, p<.OO2). The post-DST plasma cortisol and ACTH levels were also significantly correlated (râ .69, N=22, p<.OOl). Although the blood samples were drawn only at 4:00 p.m. and, due to the short half-life of ACTH, preceding ACTH level peaks causing a cortisol elevation at 4:00 p.m. may have been missed, these results support a close link between ACTH and cortisol secretion following administration of dexamethasone in healthy probands and psychiatric inpatients. Our results, therefore, support those of Reus et al.