Abstract outline for PAS 2006

ACTH and Cortisol Response to Stress in Critically Ill Term and Near-Term Newborns

Erika Fernandez MD, Rebecca Montman RN, Kristi Watterberg MD

University of New Mexico School of Medicine

Background:

Relative adrenal insufficiency, an inadequate cortisol response to significant illness, has been reported in critically ill term and near-term newborns (Fernandez et al, J of Perinatol 2005;24:114-8). Recently, we reported very low cortisol values in acutely ill infants, but appropriate responses to ACTH stimulation (Fernandez et al, Pediatric Res 2005: 1502A). The etiology of this relative adrenal insufficiency in the newborn is unclear.

Objective:

To investigate ACTH and cortisol responses to stress in critically ill term and near-term newborn infants and to describe the relationship of these values to measures of clinical illness.

Design/Methods:

In this prospective cohort study, we measured ACTH concentrations and basal and ACTH-stimulated cortisol values in mechanically ventilated infants ≥ 34 weeks and ≤ 3 days old with indwelling vascular lines. ACTH and basal cortisol values were measured, then 1mcg/kg of Cosyntropin (1-24 ACTH) was given IV. 60 minutes later, stimulated cortisol values were measured. Blood for ACTH was drawn in cold EDTA tubes, centrifuged cold and frozen until analysis by chemiluminescence (Immulite 2000, Diagnostic Products Corp., Los Angeles, CA, U.S.A). Data included SNAP scores and vasopressor requirement.

Results:

6 newborns with mean ± SD birth weight of 2815 ±528g were studied. All infants were receiving vasopressors at the time of study. SNAP scores were median (range) 17 (1011-53). Median (range) basal and ACTH-stimulated cortisol values were 3.9 XX (2.2-8.12.2-4.3) mcg/dl, and 45.942 (21-49.655.5) mcg/dl. ACTH values were 9.9 (4.9undetectable-13.6) pg/ml. There was no correlation of these values to SNAP score (r = X, p= X).

Conclusion:

These critically ill newborns showed signs of relative adrenal insufficiency. They had very low cortisol values in the face of acute illness, but responded appropriately to exogenous ACTH stimulation. Additionally, their ACTH values were much lower than reported values in un(shouldn’t it be stressed, not unstressed?) stressed infants and children. InP previous reports studies showed that on preterm infants respond to , exogenous CRH administration has resulted with appropriate increases in an elevation ofin ACTH. Therefore, we speculate that the hypothalamic-pituitary-adrenal axis dysfunction found in a significant number of critically ill term and near-term infants may originate from problems with insufficient CRH production and/or secretion.