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 secretion and decreased somatic growth. However, little is known about the relation between endogenous cortisol and GH secretion under physiological 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 prepubertal 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 NCCAH patients than in controls, whereas there was no difference in the total 24-h cortisol secretion between the two groups. The nocturnal increase 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 cross-correlation analysis of the 24-h raw data showed that cortisol and GH were negatively correlated at brief lag times of 0-30 min, and positively correlated at long lag times of 12-12.5 h in both groups, with cortisol leading GH. The negative correlation might reflect either the negative effect of glucocorticoids on the adrenergic system, which stimulates GH secretion through GH-releasing hormone (GHRH) elevations and somatostatin (SRIH) decreases, or the absence of an inhibitory effect of CRH on SRIH. The positive correlation may reflect the positive effect of glucocorticoids on the GH gene. In conclusion, NCCAH children have 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 both negative and positive influences on GH secretion, with mild disturbances in cortisol biosynthesis associated with slight alterations of GH secretion.