الفهرس 
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Abstract
Summary and Conclusions
Activation of the hypothalamic pituitary adrenal axis (HPA) is one of several important responses to stressful events and critical illness.
The hypothalamic-pituitary-adrenal (HPA) axis is essential for maintaining homeostasis in the fetus and newborn.
As circulating cortisol in early weeks of life can be significantly affected by both an intrinsic transient productive failure because of immaturity of the hypothalamic-pituitary-adrenal (HPA) axis and extrinsic stressful events or antenatal drug usage, it is, therefore, not difficult to understand why serum cortisol concentration may vary widely within this period .
Relative adrenal insufficiency occurs during an acute illness when the patient fails to mount an adequate cortisol response. Symptoms in adults and children include hypotension and electrolyte abnormalities, symptoms commonly seen in low birth weight (LBW) infants
There is scant information regarding occurrence or manifestation of relative AI in the late preterm and term new born infant. Although several small series have reported a high incidence of low cortisol values in sick term infant, there is no currently accepted definition of relative AI in these infants.
We under took this study to determine cortisol and ACTH serum levels in critically ill term and late preterm newborn and correlate their values with the severity of illness assessed by Score of Neonatal acute physiology (SNAP score).
Sixty full term and late preterm newborns were prospectively included in this study . This study was conducted at Benha Teaching Hospital, Neonatal Intensive Care Unit in the period between January 2011 to July 2012. they were 26 (45%)male and 34 (55%) female. Their gestational age ≥ 34 weeks and their post natal age were ≤ 5 days . they were classified into; group I (40 ) full term and late preterm neonates who are critically ill and mechanically ventilated and group ΙΙ(20) full term and late preterm neonates who are enterally fed, never been mechanically ventilated and not hypoglycemic at time of testing. All patients were subjected to full medical history, thorough clinical examination, assessment of severity of illness by SNAP scores, details of mechanical ventilation. also they were subjected to the following investigations ;chest x-ray, CBC, CRP, ABG, and serum cortisol and ACTH levels.
In this study there were no statistically significant differences between critically ill neonate (who are mechanically ventilated) and the control group as regard mode of delivery, body weight, maternal risk factors and gestational age.
As regard sex there were no significant differences between male and females in case and control group and there were no significant differences in mean level of serum cortisol or ACTH in cases as regard sex, gestational age or mode of delivery.
As regard CBC there were no significant differences between the two groups in Hb or platelets counts but there were significant increases in mean TLC counts in cases group as compared to control.
This study showed that there was no significant difference between all studied groups regarding PH, Pco2 &Hco3 but showed highly significant decrease of Po2 in critically ill neonates than control group. Also there was no significant statistical correlation between cortisol or ACTH and all ABGs parameters. The study showed significant correlation between cortisol, ACTH and TLC and Platelets counts.
Regarding the use of vasopressor drugs there was 15% of cases receiving dopamine, 15% receiving dopamine and doputamine , 70% not receiving vasopressor drugs. Also there was no significant difference in serum cortisol or ACTH between critically ill neonates that receive vasopressor drugs (p values 0.658, 0.179) and those not receiving.
As regard diagnosis of cases 5% of cases were ventilated due to recurrent apnea , 2.5% were aspiration pneumonia ,10% were hypoxic ischemic encephalopathy, 5% were infants of diabetic mothers ,10% were MAS, 2.5% were sepsis, 2.5% were persistent pulmonary hypertension ,2.5% Pierre Rhobin Syndrom, 30% were RDS, 7.5% were TTN ,5% were congenital diaphragmatic hernia, 5% were congenital pneumonia, 7.5% were post arrest, 2.5% were sepsis, and 2.5% were suspected inborn errors of metabolism.
Regarding mean level of serum cortisol and ACTH it showed highly significant decrease in mean level of serum cortisol and ACTH in cases (5.61±3.35μg / dl) (8.22± 5.1pg / ml) than control group (19.7±10.9 μg /dl)(( 37.75±16.57 pg/ ml). Our study showed appropriate response to exogenous ACTH in both case group (5.6±3.35µg/41.0±10.2) and in control group ( 19.7±10.6 / 43.2± 9.6).
In this work, SNAP score was calculated in cases group. It showed that 60% of cases were severely ill, 25% were moderately ill and 15% were mildly ill. On correlating SNAP score and cortisol and ACTH level it was revealed that no significant statistical correlation between SNAP score and cortisol or ACTH.
from this results we can demonstrate that Low cortisol and ACTH concentration in the majority of critically ill full term and late preterm newborn without the expected increase in response to critical illness, with normal response to exogenous ACTH could be due to inadequate response to critical illness in these newborns does not result from adrenal dysfunction .We therefore hypothesize that this is a secondary insufficiency arising from inadequate stimulation of the adrenal gland.
Conclusion:
1- Low cortisol and ACTH concentration was found in the majority of critically ill full term and late preterm newborn without the expected increase in response to critical illness ,however ,their response to exogenous ACTH was normal . These results demonstrate that the inadequate response to critical illness in these newborns does not result from adrenal dysfunction .We therefore hypothesize that this is a secondary insufficiency arising from inadequate stimulation of the adrenal gland .
2- No relationship between SNAP score as a measure of severity of illness in critically ill neonates and serum cortisol or ACTH.