ESPE Abstracts (2016) 86 P-P1-26

Sex-Specific Differences in Hypothalamus-Pituitary-Adrenal Axis Activity in Newborns with Very Low Birth Weight

Bibian van der Voorna, Marita de Waarda, Joost Rotteveela, Michaela Hartmannb, Johannes van Goudoevera, Harrie Lafebera, Stefan Wudyb & Martijn Finkena

aVU University Medical Center, Amsterdam, The Netherlands; bJustus Liebig University, Giessen, Germany

Background: Male preterm infants are at increased risk of neonatal mortality when compared to their female counterparts. The mechanisms explaining this male disadvantage are not fully elucidated yet.

Objective and hypotheses: To compare glucocorticoid metabolite excretion in urine obtained at day 10 between male and female infants born with a very low birth weight (VLBW; i.e. <1500 g). We hypothesized that male preterm infants have impaired adrenocortical function.

Method: Over a 4-h period, urine was collected of 40 infants (20 boys), who were born at a gestational age of 27.5±1.6 weeks with a birth weight of 1022±257 g. Glucocorticoid metabolites were measured using gas chromatography-mass spectrometry. Main outcome measures were: i) sum of all glucocorticoid metabolites, as an index of cortisol production rate (CPR), (ii) cortisol excretion, and iii) ratio of 11-OH/11-OXO metabolites, as an estimate of 11β-hydroxysteroid dehydrogenase (11β-HSD) activity. Differences between males and females, including interaction with Score of Neonatal Acute Physiology Perinatal Extension-II (SNAPPE II) and sepsis, were assessed by linear regression analysis. Analyses were corrected for gestational age (GA).

Results: Boys and girls did not differ in perinatal characteristics, including GA, birth weight, illnesses and nutrition. No differences between sexes were found for CPR, cortisol or 11β-HSD activity. However, interaction between sex and SNAPPE II on 11β-HSD activity was observed (P=0.02), with the interconversion favouring cortisone in males with lower SNAPPE II. Furthermore, there was a tendency towards a lower CPR and cortisol excretion in males with sepsis (interaction P=0.09 and 0.07, respectively).

Conclusion: This study provides some evidence for sex-specific differences in adrenocortical function in infants with VLBW. These patterns might contribute to sex-specific differences in neonatal mortality. Future research is necessary to explore sex-specific characteristics in steroid metabolism and its influencing factors in infants with VLBW.

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