Factors predictive of serum cortisol in pediatric patients with acute physiological stress: a cohort study

Measuring cortisol is crucial for assessing adrenal function in patients under stress; however, its value can fluctuate owing to various clinical factors. This study aimed to identify predictors of cortisol levels in pediatric patients with acute physiological stress. Children who were urgently admitted to the general ward or pediatric intensive care unit for acute illness or postoperative care were enrolled, while those with suspected adrenal function abnormalities or on current steroid therapy were excluded. Cortisol was measured in serum samples collected within 72 h of registration and its association with clinical factors was explored. A total of 397 samples from 217 patients were analyzed between August and November 2021 showing a median cortisol level of 375 nmol/L (interquartile range: 190-646 nmol/L). Multiple regression analysis with a mixed-effects model identified the following predictors of higher cortisol levels: heart rate z-score (+43.8 nmol/L/point), body temperature (+42.3 nmol/L/°C), Pediatric Early Warning System score (+44.3 nmol/L/point), age 3-6 yr (+68.8 nmol/L vs. < 1 yr), elapsed time < 4 h (+130.9 nmol/L vs. 4-12 h), and sampling time 6-10 AM (+96.4 nmol/L vs. 10 AM-2 PM). These variables independently predicted cortisol levels in pediatric patients during acute physiological stress.