Pro-opiomelanocortin and ACTH-cortisol dissociation during pediatric cardiac surgery

Area of Science:

• Endocrinology
• Pediatric Critical Care
• Hormone Regulation

Background:

• Critically ill adults exhibit high cortisol, low ACTH, and high POMC.
• Glucocorticoids reduce ACTH but not POMC in adults.
• Pediatric cardiac surgery induces critical illness, impacting the HPA axis.

Purpose of the Study:

• To investigate pro-opiomelanocortin (POMC) and adrenocorticotropic hormone (ACTH) levels in pediatric patients undergoing cardiac surgery.
• To determine the impact of glucocorticoid administration on POMC and ACTH levels in this population.
• To explore the hypothesis of a centrally activated HPA axis with altered pituitary processing.

Main Methods:

• Plasma samples collected from 53 pediatric patients (0-36 months) pre-operatively, intraoperatively, and on post-operative days 1 and 2.
• Plasma samples also collected from 24 healthy children for comparison.
• Quantification of plasma POMC and ACTH levels.

Main Results:

• Patients showed supra-normal POMC pre-operatively (p<0.0001), which normalized post-operatively (p<0.05).
• ACTH levels were not elevated in patients; they were suppressed by post-operative day 1 in glucocorticoid-naive patients (p<0.0001).
• Glucocorticoid-treated patients exhibited suppressed ACTH intraoperatively (p≤0.0001), indicating accelerated suppression.

Conclusions:

• Pre-operative elevation of POMC without increased ACTH suggests central HPA axis activation and reduced pituitary POMC processing in pediatric cardiac surgery patients.
• Glucocorticoid treatment accelerates ACTH suppression in these critically ill children.
• Findings highlight distinct HPA axis dynamics in pediatric critical illness compared to adults.