1036

Abstract

Introduction: Serum free cortisol level is gaining acceptance as the appropriate marker for critical illness related corticosteroid insufficiency (CIRCI). Cortisol levels in saliva are in equilibrium and correlate well with serum free cortisol. Although, salivary cortisol has been shown to correlate well with serum free cortisol in critically ill adults, no studies have been conducted to establish the relationship in critically ill children. Hypothesis: We hypothesize that salivary cortisol levels in critically ill children correlate with plasma free cortisol levels and can be used as a marker for CIRCI in children. Methods: This is a prospective observational study in which salivary cortisol (Salivette® collection system), serum free cortisol and serum total cortisol were measured simultaneously in 37 critically ill children admitted to a tertiary care Pediatric Intensive care unit. Samples were collected between the hours of 8am and 12 pm and within 24 hours of admission. Patients were excluded if they had bleeding or coagulopathy, abnormal LFT’s, were receiving steroids or had steroids in the last month. Patients who did not have both salivary and serum free cortisol results available were excluded from the statistical analysis (n=17). The association between free and salivary cortisol was estimated using the Pearson correlation coefficient with 95% confidence interval. Results: Salivary and serum free cortisol values from 20 patients had a correlation coefficient (r) of 0.92 (95% Confidence Interval 0.79 – 0.97). The total serum and salivary cortisol values had a correlation coefficient (r) of.76 (95% Confidence interval.45-.90) and the total serum and serum free cortisol values had a correlation coefficient (r) of.86 (95% Confidence interval.64-.94). Conclusions: Serum free and salivary cortisol values correlate in critically ill children. Salivary cortisol is a cost effective and less invasive measure of bioavailable cortisol and offers an alternate and accurate method for assessing CIRCI in children.