THE HYPOTHALAMIC-PITUITARY-ADRENAL AXIS IN PRETERM INFANTS WEIGHING LESS-THAN-OR-EQUAL-TO-1250G - ASSOCIATION WITH PERINATAL DATA AND CHRONIC LUNG-DISEASE

The hypothalamic-pituitary-adrenal axis (HPA) was examined in 34 venti lated preterm infants weighing less than or equal to 1250g during the first week of life to evaluate the association between adrenal suppres sion and subsequent chronic lung disease. The second aim of the study was to detect perinatal and clinical differences between the infants w ith and without persistent suppression of the HPA after completion of dexamethasone treatment for chronic lung disease. To evaluate the HPA, the corticotropin-releasing hormone stimulation test was performed, a nd the cortisol and adrenocorticotropic hormone (ACTH) levels were mea sured by radioimmunoassay. No association could be found between the s ynthesis of cortisol and ACTH at the end of the first week of life and the development of chronic lung disease. After treatment with dexamet hasone, baseline cortisol levels < 138 nmol l(-1) were found in 12 inf ants (46.2%), 8 of whom (30.8%) had cortisol values below 83 nmol l(-1 ). The perinatal data of these patients did not differ from infants wi thout HPA suppression. However, the infants with cortisol levels < 83 nmol l(-1) after dexamethasone showed a significantly shorter need for mechanical ventilation and supplemental oxygen (p < 0.01) and a lower incidence of chronic lung disease (p < 0.05).