A-335 Pediatric Cortisol Reference Intervals (RI): Impact of Age-Specific RI on the Rate of Abnormal “Low” Cortisol Results

Abstract Background Serum cortisol, measured by automated immunoassay, is a rapid test used for the initial assessment of adrenal dysfunction. Physiologic serum cortisol concentrations are influenced by many factors including diurnal variation, stress, and patient age. In the absence of established pediatric reference intervals (RIs), our laboratory has utilized adult RIs to flag pediatric cortisol results as abnormally high or low in the electronic health record. However, pediatric cortisol RIs recently defined by the Canadian Laboratory Initiative on Pediatric Reference Intervals (CALIPER) are considerably lower than the adult RIs currently in use. This could cause pediatric cortisol results to be incorrectly flagged as “low” when they are within the age-specific RI and lead to unnecessary follow-up testing. The aim of this study was to determine the impact of implementing CALIPER pediatric cortisol RIs on the rate of “low” result flagging for pediatric patients. Methods AM cortisol results for patients age