Initial observations regarding free cortisol quantification logistics among critically ill children

Elevated Baseline Cortisol Levels Are Predictive of Bad Outcomes in Critically Ill Children

OBJECTIVE

The definition of an adequate adrenal response in critically ill children continues to be controversial. We aimed to evaluate the cortisol levels at baseline and after adrenocorticotropin (ACTH) stimulation and determine their association to clinical outcome of critically ill children.

METHODS

All children who underwent an ACTH test in the pediatric intensive care unit (PICU) in a tertiary medical center between 2006 and 2013 were included in the study. Data on age, sex, diagnosis, vasoactive-inotropic score, length of pediatric intensive care unit stay, and mortality were obtained. Laboratory variables included hematologic and chemistry data, arterial lactate, and total plasma cortisol levels at baseline and after ACTH stimulation.

RESULTS

Ninety-nine patients (61 males; median [range] age, 2 [0-204] months) were enrolled. The mortality rate of children with a baseline cortisol level of 600 nmol/L or greater was 36% (12/33 patients) versus 18% (12/66 patients) for children with a baseline cortisol level of less than 600 nmol/L (odds ratio, 2.6 [95% confidence interval, 1-6.6]; P = 0.05). There was a positive correlation between baseline cortisol and lactate levels (r = 0.40, P < 0.0001), vasoactive-inotropic scores (r = 0.24, P = 0.02), and mortality (P = 0.05). There was no correlation between peak cortisol measured at the ACTH test or the delta increment of cortisol from baseline and mortality.

CONCLUSIONS

A high baseline cortisol level in critically ill children was associated with more severe illness, higher lactate level, and a higher mortality rate. Routine baseline cortisol assessment is recommended to identify patients at high mortality risk.

Random serum free cortisol and total cortisol measurements in pediatric septic shock

Background The aim of the study was to examine the relationship between serum total cortisol (TC) and free cortisol (FC) levels in children with septic shock and the relationship of these levels with baseline illness severity. Methods A sub-study of a randomized controlled trial (RCT) of hydrocortisone vs. placebo in pediatric septic shock conducted in seven academic pediatric intensive care units (PICUs) in Canada on children aged newborn to 17 years. Thirty children with septic shock had serum sent for TC and FC measurement within 6 h of meeting the study eligibility criteria. Results Baseline FC and TC levels were strongly correlated with baseline Pediatric Risk of Mortality (PRISM) score (R2=0.759, p<0.001; R2=0.717, p<0.001) and moderately correlated with admission Vasotropic Inotropic Score (VIS) (R2=0.489, p<0.001; R2=0.316, p<0.001). Serum TC levels were highly correlated with FC levels (R2=0.92, p<0.001) and showed strong agreement (R2=0.98, p<0.001 on a Bland-Altman plot). The ratio of FC to TC moderately correlated with TC levels (R2=0.46, p<0.001) but did not correlate with baseline albumin levels (R2=0.19, p=0.13). Conclusions Random TC and FC levels are strongly correlated, show strong agreement and are reflective of illness severity in children with septic shock. As such, isolated FC measurement does not appear to provide added information relative to TC in acutely ill children with septic shock.

Measurement of salivary cortisol level for the diagnosis of critical illness-related corticosteroid insufficiency in children

OBJECTIVE

To compare serum total, serum free and salivary cortisol in critically ill children.

DESIGN

Prospective observational cohort study.

SETTING

Tertiary pediatric critical care unit at Ronald McDonald Children's Hospital at Loyola University Medical Center.

PATIENTS

We enrolled 59 patients (4 weeks to 18 years of age) between January 2012 and May 2013. Thirty-four patients were included in the salivary to serum free cortisol correlational analysis.

INTERVENTIONS

Blood and saliva samples were obtained simultaneously within 24 hours of admission between the hours of 6 AM and 12 PM. Salivary cortisol was tested by liquid chromatography/tandem mass spectrometry, serum free cortisol by liquid chromatography/tandem mass spectrometry followed by equilibrium dialysis, and serum total cortisol by liquid chromatography/tandem mass spectrometry.

MEASUREMENTS AND MAIN RESULTS

Salivary and serum free cortisol values from 34 patients had a correlation coefficient (r) of 0.87 (95% CI, 0.75-0.93; p < 0.0001). The total serum and salivary cortisol values had a correlation coefficient (r) of 0.67 (95% CI, 0.42-0.81; p < 0.0001). The total serum and serum free cortisol values had a correlation coefficient (r) of 0.83 (95% CI, 0.69-0.91; p < 0.0001).

CONCLUSIONS

Serum free and salivary cortisol values correlate in critically ill children. Salivary cortisol can be used as a surrogate for serum free cortisol in critically ill pediatric patients. Salivary cortisol is a cost-effective and less invasive measure of bioavailable cortisol and offers an alternate and accurate method for assessing critical illness-related corticosteroid insufficiency in children.

Reduced glucocorticoid receptor protein expression in children with critical illness

BACKGROUND/AIMS

The diagnostic criteria for critical illness-related corticoid insufficiency (CIRCI) are not well established, particularly for children. In addition to alterations in adrenal function, cellular resistance to glucocorticoid action could contribute to CIRCI due to alterations in the functioning of the intracellular receptor protein for corticosteroids, the glucocorticoid receptor (GR).

METHODS

We have therefore undertaken a pilot, prospective study to assess whether cellular GR activity can be measured in peripheral blood mononuclear cells (PBMCs) from critically ill children.

RESULTS

Total and cytoplasmic, but not nuclear GR levels were significantly lower in PBMCs from critically ill children (i.e. sepsis/septic shock and traumatic brain injury) compared to healthy controls . While total cortisol concentrations did not differ between test groups, salivary and serum-free cortisol concentrations were significantly greater in both groups of children with critical illness. Cortisol-binding globulin levels were significantly lower in patients with sepsis/septic shock.

CONCLUSIONS

The lower total and cytoplasmic receptor levels in critically ill children suggest that the GR-mediated response to exogenous glucocorticoid therapy may be limited. However, the nuclear transport of GR in critically ill patients suggests that residual receptors in these patients retain functionality and may be accessible to therapeutic treatments that maximize their activity.

Common endocrine issues in the pediatric intensive care unit

Thyroid hormone is central to normal development and metabolism. Abnormalities in thyroid function in North America often arise from autoimmune diseases, but they rarely present as critical illness. Severe deficiency or excess of thyroid hormone both represent life-threatening disease, which must be treated expeditiously and thoroughly. Such deficiencies must be considered, because presentation may be nonspecific.