THE PITUITARY-ADRENAL RESPONSE
TO EXOGENOUS HUMAN CORTICOTROPIN-RELEASING HORMONE IN VERY LOW BIRTH WEIGHT
INFANTS
Y. Nako, T.
Tomomasa, A. Morikawa
Department of
Pediatrics, Gunma University, Gunma, Japan
Objective: We
performed human corticotropin-releasing hormone (hCRH) stimulation test in
very low birth weight (VLBW) infants to evaluate the relationship between
the function of the hypothalamic-pituitary-adrenal (HPA) axis and the
complications including chronic lung disease [CLD] at very early neonatal
period.
Methods:
Thirty-four VLBW infants were enrolled. Plasma ACTH and serum cortisol
concentrations were measured before (baseline) and 30 min after iv hCRH (1
µg/kg) on median day of 2.
Results: The median plasma ACTH concentrations rose
significantly from a baseline value of 5.3 to 7.9 pmol/L (P=.0001) at 30
min. The serum cortisol concentrations rose significantly from 368 at
baseline to 573 nmol/L (P<.0001) at 30 min. Both basal (P=.0003) and
stimulated (P=.002) serum cortisol concentrations of infants with CLD were
significantly higher than those of infants without CLD. However, the delta
cortisol was not significantly different between the two groups. The median
postnatal age (day) of hCRH test with negative delta cortisol (n=8) were
significantly earlier than that with positive (n=26) [2 vs. 2.5, P<.04].
Conclusion:
VLBW infants can respond to exogenous hCRH within a week after birth,
except for the very early postnatal age relating with probable residual
hormonal effect(s) of placenta. We consider the HPA axis of VLBW infants
under stresses can act during the early neonatal period.