Serum cortisol concentrations in ill preterm infants less than 30 weeks gestational age

Adrenal insufficiency is suspected in some ill preterm infants. The aim of this prospective study was to compare serum cortisol concentrations during the first 2 wk of life of well preterm infants (group A) less than 30 wk of gestational age with the cortisol concentrations of ill preterm infants wh ose arterial hypotension-a potential sign of adrenal insufficiency-had been treated with catecholamine (group B), and the cortisol concentrations of i ll preterm infants who had not been so treated (group C). Cortisol concentr ations did not differ significantly between group A (240 nmol/l, 58-659; n = 46) (median, minimum-maximum) and group C (268 nmol/l, 58-1007; n = 25). Group B had a double-peaked distribution of cortisol. Two subgroups were fo rmed by taking the highest cortisol level of group A as a threshold: group B1 (110 nmol/l, 41-378; n = 20) and group B2 (1200 nmol/l, 764-1482; n = 8) . The cortisol concentrations of group B1 were significantly lower (p = 0.0 0097) compared to the cortisol concentrations of the well preterm infants ( group A). The severity of illness, which was quantified by two scoring syst ems, differed significantly among the groups (p < 0.003 for all comparisons ) with the following sequence: A < C < B, but not between B1 and B2, as cli nical variables were not different between the subgroups. In conclusion, when clinical signs of adrenal insufficiency, such as severe arterial hypotension;were not found in ill preterm infants, serum cortisol concentrations were not different from those of well preterm infants. Seve nty-one percent of preterm infants with catecholamine-treated arterial hypo tension had significantly lower cortisol concentrations, which may reflect adrenal insufficiency, but no differences in the severity of illness were f ound between infants with high and low cortisol levels.