The timing of administration of exogenous glucocorticoid affects 24 hour growth hormone secretion in children

Abstract

Exogenous glucocorticoids may suppress linear growth by affecting the diurnal secretory rhythm of GH. ObjectiveTo assess whether the timing of exogenous glucocorticoid administration affects GH secretion in children. DesignFour girls and four boys aged 10.6 to 15.8 (mean 13.2) years with normal weight and height and pubertal stages I–IV were studied in an open randomized 2-period cross-over trial, with a 1-day un-in, and two 4-day periods of 5mg prednisolone in the morning or in the evening, respectively, separated by a 3-week washout period. At run-in and on the last day of each treatment period serum was collected every 20min for 24h for assessment of GH. Secondary analyses were serum levels of IGF-I and IGFBP-3 (measured every 8h), and IGFBP-1, insulin, and collagen markers PICP, PINP, ICTP and PIIINP (measured every 2h). ResultsEvening prednisolone suppressed 24hour GH secretion (P=0.016), overnight GH secretion (P=0.023) and IGF-I (P=0.024) when compared to morning prednisolone, but not when compared to run-in. Evening prednisolone also increased nocturnal insulin levels as compared to run-in (P=0.010). Irrespective of time of day, prednisolone increased serum collagen markers PICP, PIINP, ICTP and PINP (all P<0.05). ConclusionsShort-term prednisolone 5mg administered in the morning may alleviate nocturnal GH suppression as compared to evening administration. In analogy, growth rates are less affected by morning as compared to evening administration of exogenous glucocorticoids. In contrast, collagen markers and metabolic indices were not affected by the timing of prednisolone administration.