DIFFERENCES IN THE HYPOTHALAMIC-PITUITARY-ADRENAL (HPA) AXIS OF BLACK AND WHITE GIRLS. |[dagger]| 591

We have previously shown that CRH-stimulated ACTH levels are much higher in black than in white adults, while cortisol values are similar (JCEM 1993; 77:536-41; Horm. Res. 1995; 44:208-212). Because a number of racial differences in physiology become apparent only after the onset of puberty, we hypothesized that CRH-stimulated ACTH would be similar in blacks and whites before the onset of puberty. We studied the HPA axis of 19 black and 19 white normal weight girls (age 8-10y) matched for socioeconomic status, age, body mass index, and pubertal stage. Waist circumference, waist:hip ratio, basal free cortisol and cortisol binding globulin, and the ACTH and cortisol responses to 1 μg/kg ovine CRH were measured. There were no racial differences in waist circumerence, waist:hip ratio, basal free cortisol, cortisol binding globulin, basal cortisol or ACTH, or in cortisol response to CRH. However, CRH-stimulated ACTH was significantly greater in blacks from 15 min to 90 min after administration of CRH (area under curve 1754 ± 121 pmol/L · min in blacks vs 1304 ± 124 in whites, p<0.001).Figure We conclude that CRH-stimulated ACTH is greater in blacks than whites even before the onset of puberty.