Measurement of tissue cortisol levels in patients with severe burns: a preliminary investigation

Abstract

IntroductionThe assessment of adrenal function in critically ill patients is problematic, and there is evidence to suggest that measurement of tissue glucocorticoid activity may be more useful than estimation of plasma cortisol concentrations. Interstitial cortisol concentrations of cortisol represent the available pool of glucocorticoids able to enter the cell and bind to the glucocorticoid receptor. However the concentrations of plasma cortisol may not accurately reflect interstitial concentrations. We elected to perform a preliminary study into the feasibility of measuring interstitial cortisol by microdialysis, and to investigate the relationship between total plasma cortisol, free plasma cortisol and interstitial cortisol in patients with severe burns.MethodsA prospective observational study carried out in a tertiary intensive care unit. Ten adult patients with a mean total burn surface area of 48% were studied. Interstitial cortisol was measured by microdialysis from patient-matched burnt and non-burnt tissue and compared with that of 3 healthy volunteers. Plasma sampling for estimations of total and free cortisol concentrations was performed concurrently.ResultsIn the burn patients, mean total plasma and free plasma cortisol concentrations were 8.8 +/- 3.9, and 1.7 +/- 1.1 mcg/dL, (p < 0.001), respectively. Mean subcutaneous microdialysis cortisol concentrations in the burn and non-burn tissue were 0.80 +/- 0.31 vs 0.74 +/- 0.41 mcg/dL (p = 0.8), respectively, and were significantly elevated over the mean subcutaneous microdialysis cortisol concentrations in the healthy volunteers. There was no significant correlation between total plasma or free plasma and microdialysis cortisol concentrations. Plasma free cortisol was better correlated with total burn surface area than total cortisol.ConclusionsIn this preliminary study, interstitial cortisol concentrations measured by microdialysis in burnt and non-burnt skin from patients with severe thermal injury are significantly elevated over those from healthy volunteers. Plasma estimations of cortisol do not correlate with the microdialysis levels, raising the possibility that plasma cortisol may be an unreliable guide to tissue cortisol activity.

Loss of Cortisol Circadian Rhythm in Patients with Traumatic Brain Injury: A Microdialysis Evaluation

“…Some groups have used microdialysis technique in burnt [4] and TBI [5] patients in a preliminary form, suggesting that total serum cortisol may not appropriately reflect the cortisol tissue availability [4,5].…”

“…Microdialysis techniques have recently allowed measuring interstitial cortisol in critically ill patients [4,5]. A previous study in patients with diffuse TBI showed that brain interstitial cortisol presented a weak correlation with total serum cortisol in half of TBI patients evaluated [5], suggesting that serum cortisol may not reflect brain cortisol availability in most TBI patients.…”

Critical Illness-Related Corticosteroid Insufficiency in Children

“…Moreover, reduced cortisol breakdown contributed to hypercortisolemia and hence ACTH suppression [20]. Other studies have focused on the tissue and cellular adaptation during stress, including measurement of the tissue cortisol concentration [21] and its activity [22,23]. The activation of the HPA axis during stress is depicted in figure 1.…”

“…Emerging data suggest that there may be abnormalities in the tissue activity of glucocorticoids in critically ill patients, and that plasma profiles may not be reliable indicators of tissue glucocorticoid activity [21,22]. Therefore, the decision to treat with corticosteroids should be based on clinical criteria and not on the results of adrenal function testing.…”

Individualizing Optimal Fluid Resuscitation in Patients with Major Burns: Emerging Role for Hydrocortisone, Proteinuria and Brain Natriuretic Peptide

“…It is unclear however, whether cortisol indices can be used to judge the necessity to start therapy for reduction of capillary leakage. Tissue cortisol levels are increased in burn patients, but, they do not correlate to plasma cortisol [20]. Moreover, use of hydrocortisone as intervention in severely burned patients to improve hemodynamic stability based on corticotropin tests for adrenal insufficiency did not predict the effects of hydrocortisone intervention [21].…”