RESPONSE OF THE HYPOTHALAMIC-PITUITARY-AD RENAL-AXIS TO CORTICOTROPIN-RELEASING-HORMONE IN PRETERM INFANTS WITH BRONCHOPULMONARY DYSPLASIA AFTER TREATMENT WITH DEXAMETHASONE

Background The purpose of this prospective study was to examine the hy pothalamic-pituitary-adrenal axis using the corticotropin-releasing ho rmone stimulation test in 24 preterm infants (mean gestational age 27. 4+/-1.4 weeks, mean birth weight 997+/-166 g) with bronchopulmonary dy splasia after completion of dexamethasone treatment. Methods The CRH s timulation test was performed before and two days after the course of dexamethasone therapy in a dosage of 1 mu g/kg body weight. Blood samp les were obtained before and 30 minutes after application of CRH. The blood values for cortisol and ACTH were measured by radioimmunoassay. Results The mean basal cortisol level was significantly reduced from 3 381+/-283 nmol/l before dexamethasone treatment to 153+/-102 nmol/l af ter dexamethasone therapy. The site of HPA suppression was located to the pituitary gland as the mean basal ACTH level dropped from 9.5+/-5. 2 pmol/l to 5.6+/-2.0 pmol/l after the dexamethasone course. In 9 infa nts there was only an insufficient increase of cortisol level after ap plication of CRH as a possible sign of a reduced adrenal response. The patients with HPA-suppression did not differ in clinical aspects from infants without suppression of the HPA. Conclusion The results demons trate a significant suppression of the adrenal and pituitary gland in very low birth weight infants with bronchopulmonary dysplasia after de xamethasone treatment. Before stressful situations like surgery we the rfore recommend an investigation of the HPA.