SPONTANEOUS CORTISOL AND GROWTH-HORMONE SECRETION INTERACTIONS IN PATIENTS WITH NONCLASSIC 21-HYDROXYLASE DEFICIENCY (NCCAH) AND CONTROL CHILDREN

Both exogenous and endogenous hypercortisolism result in reduced GH se cretion and decreased somatic growth. However, little is known about t he relation between endogenous cortisol and GH secretion under physiol ogical or slightly disturbed conditions. To examine this, we measured and evaluated the pulsatility and circadian rhythmicity, and we cross- correlated the secretory patterns of cortisol and GH in six prepuberta l patients with nonclassic 21-hydroxylase deficiency (NCCAH) and seven age-matched short-normal children. Cortisol and GH were secreted in a pulsatile fashion in both the NCCAH and control groups. The nocturnal peak cortisol increment and time-integrated area were lower in the NC CAH patients than in controls, whereas there was no difference in the total 24-h cortisol secretion between the two groups. The nocturnal in crease of GH in NCCAH children, on the other hand, was associated with a significant augmentation of the pulse amplitude, whereas in control children there was an elevation of the baseline component. The crossc orrelation analysis of the 24-h raw data showed that cortisol and GH w ere negatively correlated at brief lag times of 0-30 min, and positive ly correlated at long lag times of 12-12.5 h in both groups, with cort isol leading GH. The negative correlation might reflect either the neg ative effect of glucocorticoids on the adrenergic system, which stimul ates GH secretion through GH-releasing hormone (GHRH) elevations and s omatostatin (SRIH) decreases, or the absence of an inhibitory effect o f CRH on SRIH. The positive correlation may reflect the positive effec t of glucocorticoids on the GH gene. In conclusion, NCCAH children hav e a mild nocturnal cortisol deficiency compared with control children, as previously reported, and a distinct circadian pattern of pulsatile GH secretion. The hypothalamic-pituitary-adrenal (HPA) axis exerts bo th negative and positive influences on GH secretion, with mild disturb ances in cortisol biosynthesis associated with slight alterations of G H secretion.