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Cortisol dynamics following acute severe brain injury
Terence Savaridas1, Peter J D Andrews, Bridget Harris
1College of Medicine and Veterinary Medicine, University of Edinburgh, Teviot Place, EH8 9AG Edinburgh, Scotland.
Intensive Care Medicine
|May 13, 2004
Summary
Acute brain injury in ICU patients shows normal total cortisol but decreased corticosteroid binding-globulin (CBG). This results in elevated free cortisol, potentially indicating relative hypocortisolaemia despite critical illness.
Area of Science:
- Endocrinology
- Neuroscience
- Critical Care Medicine
Background:
- The diurnal rhythm of plasma cortisol and corticosteroid binding-globulin (CBG) is crucial for physiological regulation.
- Altered cortisol dynamics are suspected in acute severe brain injury (SBI) due to critical illness and stress.
Purpose of the Study:
- To investigate the diurnal patterns of plasma cortisol and CBG in patients with SBI managed in an intensive care unit (ICU).
- To assess whether SBI alters cortisol and CBG levels and their diurnal variations.
Main Methods:
- An observational clinical study was conducted in a 12-bed medical/surgical critical care facility.
- Fifteen patients with acute, coma-inducing brain injury (9 trauma, 6 subarachnoid hemorrhage) were included.
- Morning and evening blood samples were collected via arterial lines for cortisol and CBG analysis.
Main Results:
- Total plasma cortisol levels were generally within the normal reference range, with only a few patients exceeding it.
- Plasma CBG levels were significantly decreased in all 15 brain-injured patients.
- Eight patients exhibited diurnal variation in plasma cortisol, while no diurnal variation in CBG was detected.
- All patients had an elevated free cortisol percentage, with some showing significantly high levels.
Conclusions:
- Acute severe brain injury does not appear to elevate total serum cortisol, suggesting a state of 'relative' hypocortisolaemia.
- Reduced plasma CBG levels in SBI patients lead to an increase in plasma free cortisol.
- These findings highlight altered cortisol metabolism in SBI, with implications for stress response and management.