Antenatal glucocorticoids modulate the amplitude of pulsatile cortisol secretion in premature neonates.

We hypothesized that antenatal exposure to glucocorticoids influences subsequent pulsatile cortisol (F) secretion in premature neonates. To test this hypothesis, blood was sampled for plasma F determination via indwelling arterial lines at 15-min intervals for 6 h in 26 clinically stable neonates whose gestational ages were 25-33 wk. Deconvolution analysis was used to characterize F secretion and elimination. Pulsatile F secretion was observed in all neonates. Deconvolution estimates in eight neonates exposed to antenatal glucocorticoids (ANG group) were compared with those of 18 neonates not or only remotely exposed to ANG (No/RG group). The median amplitude of the F secretory burst of the ANG group was significantly less than that of the No/RG group [4.3 nmol/Lv x min and 9.2 nmol/Lv x min, respectively; p = 0.026 (Lv is liter of F distribution volume)]. The number and duration of F secretory bursts was similar for both groups: 5 bursts per 6 h, and 23 versus 16 min. By univariate linear regression analysis, mean arterial blood pressure correlated positively with F secretory burst frequency and F production rate (p = 0.0035, r = 0.55 and p = 0.0067, r = 0.52, respectively). We propose that ANG treatment modulates the amplitude of pulsatile F secretion in premature neonates.

Survey of the definition and screening of neonatal hypoglycaemia in Australia.

OBJECTIVE: To determine the approach to identifying neonatal hypoglycaemia and the definition of neonatal hypoglycaemia used by neonatal paediatricians in Australian Level 3 neonatal intensive care units (NICU). METHODOLOGY: A questionnaire was sent to the 101 neonatal paediatricians in the 22 Level 3 NICU in Australia asking their method of screening for, and definition of, neonatal hypoglycaemia. RESULTS: Responses were received from 70 neonatal paediatricians, including all 22 directors. A bedside glucose meter is used in 19 of 22 NICU to screen for hypoglycaemia, whilst one NICU uses a glucose analyzer and another NICU uses a visual colour comparison method. One NICU does not screen, but has blood glucose measured in a satellite laboratory. If the screening method suggests hypoglycaemia, 62 of 63 neonatal paediatricians proceed to blood glucose determination in a laboratory, mostly using plasma samples. Based on the laboratory measurement, the definition of neonatal hypoglycaemia ranged from < 1.1 to 3.0 mmol/L. CONCLUSIONS: The majority of neonatal paediatricians in Australian NICU screen for neonatal hypoglycaemia using a bedside glucose meter. There is a wide range in the definition of neonatal hypoglycaemia from < 1.1 to 3.0 mmol/L.