Differences in the hypothalamic-pituitary-adrenal axis of black girls and white girls☆☆☆★

Abstract After intravenous administration of ovine corticotropin-releasing hormone (CRH), the plasma corticotropin (ACTH) concentrations of adult black women and men are approximately twice as high as those of adult white women and men; however, there are no corresponding differences in cortisol response. To determine whether these differences in ACTH secretion are also present in prepubertal and early pubertal girls, we studied the hypothalamic-pituitary-adrenal axis of 19 black and 19 white girls of normal weight (age 7 to 10 years) who were matched for body mass index, age, and socioeconomic status. Measures of cortisol's effects, including waist circumference, waist/hip ratio, and fasting insulin and glucose levels, were obtained and related to the ACTH and cortisol responses to 1 μg/kg CRH. There were no racial differences in waist circumference, waist/hip ratio, fasting glucose or insulin levels, baseline free or total plasma cortisol levels, baseline ACTH concentrations, or the plasma cortisol response to CRH. However, CRH-stimulated plasma ACTH concentrations, measured in a polyclonal radioimmunoassay, were significantly greater in prepubertal and early pubertal black girls than in white girls at all time points between 15 and 90 minutes after administration of CRH (area under curve [AUC] 1754 ± 121 pmol/L • min in black girls vs 1304 ± 124 pmol/L • min in white girls, p p EDIATR 1996;129:130-5)