Chinese Pediatric Reference Intervals for Serum Cortisol on IMMULITE 2000.

Clinical interpretation of the test results for cortisol based on continuous reference intervals with appropriate partitions improves pediatric diagnosis; however, these values are available only for Caucasians. To develop the pediatric reference intervals for Chinese population, we examined the serum cortisol levels in 1,143 healthy Chinese children aged 4-18 years (566 boys and 577 girls), using an IMMULITE 2000 Immunoassay System (Siemens Healthcare GmbH). Phlebotomy was performed at 7-9 a.m. for 284 boys and 287 girls and at 1-3 p.m. for the others. They were divided into four age groups according to the Clinical and Laboratory Standards Institute guideline EP28-A3c, with the last group further stratified according to sampling time. Separate reference intervals of 49.6-323.7, 70.9-395.3, and 90.1-448.7 nmol/L were established for children aged 4-8, 9-12, and 13-15 years, respectively. Further, reference intervals of 118.2-464.7 and 71.4-446.7 nmol/L were established for morning and afternoon cortisol levels, respectively, in children aged 16-18 years. Further studies are necessary to transfer and validate these reference intervals in other analytical systems and pediatric populations, and to allow for broader applications.