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Serum concentrations of cortisone and cortisol in premature infants
M Fujitaka1, K Jinno, N Sakura
1Department of Pediatrics, Hiroshima University School of Medicine, Minami-Ku, Japan.
Insights
In premature infants, cortisone levels often exceed cortisol levels, even after two months. This suggests the fetal adrenal cortex remains functional longer in premature infants, impacting hormone measurement accuracy.
Area of Science:
- Endocrinology
- Neonatal Physiology
- Biochemistry
Background:
- Cortisol is the primary active glucocorticoid, while cortisone is its inactive metabolite.
- The ratio of cortisol to cortisone changes with age in healthy individuals.
- Understanding this ratio is crucial for assessing adrenal function, especially in vulnerable populations.
Purpose of the Study:
- To accurately determine the relationship between cortisol and cortisone in premature infants.
- To compare hormone levels in premature infants with those in control children and adults.
- To investigate the influence of gestational age on cortisol and cortisone concentrations.
Main Methods:
- Serum cortisone and cortisol concentrations were measured using reversed-phase high-performance liquid chromatography (HPLC).
- A study group of 232 premature infants was compared to control groups of 127 children and 88 adults.
- Data were analyzed based on the equivalent gestational age of premature infants.
Main Results:
- In premature infants, serum cortisone concentrations were consistently higher than cortisol levels, even beyond two months of age.
- Total cortisone and cortisol concentrations were similar between premature infants and controls.
- Cortisone predominated in premature infants over 32 weeks gestational age, while cortisol was higher between 24-31 weeks.
Conclusions:
- Premature infants exhibit a prolonged functional period of the fetal adrenal cortex, leading to cortisone predominance.
- Cortisone levels should not be disregarded when assessing cortisol in premature infants due to its biological inactivity.
- Simultaneous measurement of serum cortisone and cortisol is vital for accurate adrenocortical function assessment in neonates.
Abstract:
To determine the relationship between biological active cortisol and its inert metabolite cortisone accurately in premature infants, serum cortisone and cortisol concentrations were measured by reversed-phase high-performance liquid chromatography (HPLC) in a group of 232 premature infants and in a control group of 127 children and 88 adults. In the control group, serum cortisone concentrations were greater than serum cortisol levels during the first 2 months after birth; cortisol levels were higher than cortisone levels after 2 months of age. However, in premature infants, serum cortisone concentrations were greater than serum cortisol levels even after the first 2 months, and total concentrations of cortisone and cortisol were equal to those in controls. Results were then analyzed according to the equivalent gestational age of premature infants. Cortisone was predominant in premature infants older than 32 weeks of equivalent gestational age, but cortisol was higher than cortisone from equivalent gestational age 24 to 31 weeks. These findings suggest that the ability of premature infants to secrete glucocorticoids resembled that of normal controls. Also, the fetal zone of the cortex, which is associated with a predominance of cortisone, remained functional in premature infants for a longer time than in control infants. Our findings that in premature infants cortisone was predominant compared with cortisol and the sum of cortisone and cortisol was equal to that in the controls indicate that cortisone cannot be disregarded whenever the cortisol level is estimated, although cortisone itself is recognized to be biologically inactive. Simultaneous measurement of serum cortisone and cortisol concentrations is important when adrenocortical function is being determined, especially in premature infants.