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Episodic ACTH and cortisol secretion in normal children
W H Wallace1, E C Crowne, S M Shalet
1Department of Endocrinology, Christie Hospital, Manchester, UK.
Insights
In children, adrenocorticotropic hormone (ACTH) and cortisol secretion are interdependent and episodic, occurring in regular bursts throughout the day. This relationship is not affected by gender or pubertal status.
Area of Science:
- Pediatric Endocrinology
- Chronobiology
- Hormone Secretion Dynamics
Background:
- The relationship between adrenocorticotropic hormone (ACTH) and cortisol secretion is crucial for physiological regulation.
- Understanding these dynamics in children is essential for diagnosing endocrine disorders.
Purpose of the Study:
- To investigate the normal relationship between ACTH and cortisol secretion patterns in children.
- To identify periodicities and interdependencies in their release over a 24-hour period.
Main Methods:
- Hospitalized children (n=14) underwent continuous blood sampling every 20 minutes for 24 hours.
- Time series analysis and coherency techniques were employed to analyze ACTH and cortisol secretion patterns.
- Data were analyzed for circadian rhythms, dominant periodicities, and shared periodicities between hormones.
Main Results:
- A clear circadian rhythm for both ACTH and cortisol was observed, with peak levels in the morning.
- Both hormones exhibited dominant periodicities of 0.7-1.0 hours, indicating 24-34 secretory episodes daily.
- Significant shared periodicities between ACTH and cortisol were identified, suggesting interdependent secretion.
- Cortisol showed a secondary periodicity of 2-3.2 hours, not observed for ACTH.
Conclusions:
- ACTH and cortisol secretion in children are interdependent and episodic, characterized by regular bursts.
- These secretory patterns are not significantly influenced by gender or pubertal status in the studied age group.
- The findings provide a normative reference for understanding hormonal regulation in pediatric endocrinology.
Abstract:
The aim of this study was to determine the normal relationship between ACTH and cortisol secretion in children. Fourteen children (nine male, five female; median age 11.3 years) were hospitalized and blood samples were taken every 20 min for 24 h. A circadian rhythm was observed with median 0900 h and midnight ACTH values of 1.80 and less than 0.97 pmol/l, and for cortisol 296 and 62 nmol/l respectively. The median (range) areas under the curve for ACTH and cortisol were 29.7 (9.0-53.8) pmol/l/h and 5114 (3562-8630) nmol/l/h respectively. There were no significant differences detected for ACTH and cortisol secretion between males and females, or between prepubertal (n = 9) and pubertal subjects (n = 5). Using a novel form of time series analysis we have shown that both ACTH and cortisol are secreted with a dominant periodicity of 0.7-1.0 h, representing 24-34 secretory episodes of ACTH and cortisol in 24 h. For cortisol, but not ACTH, there is a significant secondary periodicity of 2-3.2 h. To look for shared periodicities we have used the technique of coherency. This reveals that for six of the children ACTH and cortisol are secreted with a significant shared periodicity of 0.8-1.0 h, and for a further five children a similar secondary shared periodicity is present. Therefore in normal children ACTH and cortisol secretion are interdependent and episodic but are not influenced by either pubertal status or gender.