title: Establishing Normal Ranges of Basal and ACTH-Stimulated Serum Free Cortisol in Children.
abstract: BACKGROUND
  Normative data have been established for stimulated serum total cortisol in children but not for serum free cortisol.
  
  
  METHODS
  Children who were referred for ACTH testing to rule out adrenal insufficiency were enrolled. Only children with normal response and normal androgen levels were included. Total cortisol was determined by a chemiluminescence method, and free cortisol was measured by the same method following equilibrium dialysis.
  
  
  RESULTS
  The study group consisted of 85 subjects (28 male; 57 female) with a median age of 8.5 years (range 0.6-17.7). The mean basal and peak total cortisol levels were 11.5 ± 5.7 and 32.9 ± 6.2 μg/dl, respectively. The mean basal and peak free cortisol levels were 0.4 ± 0.3 and 1.8 ± 0.6 μg/dl, respectively. There was a negative correlation between peak total cortisol and age but not between peak free cortisol and age. The 3rd and 97th percentile values for peak free cortisol were 0.94 μg/dl (26 nmol/l) and 2.97 μg/dl (82 nmol/l), respectively.
  
  
  CONCLUSIONS
  Measurement of free cortisol has the advantage of being independent of cortisol-binding globulin levels. This study provides reference ranges for stimulated free cortisol in children, with a cutoff value of 0.9 μg/dl (25 nmol/l) as a normal response to a standard ACTH test.
authors.affiliation: Pediatric Endocrinology and Diabetes Unit, Dana-Dwek Children's Hospital, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel.
authors.forename: Ori
authors.initials: O
authors.lastname: Eyal
authors.forename: Rona
authors.initials: R
authors.lastname: Limor
authors.forename: Asaf
authors.initials: A
authors.lastname: Oren
authors.forename: Anita
authors.initials: A
authors.lastname: Schachter-Davidov
authors.forename: Naftali
authors.initials: N
authors.lastname: Stern
authors.forename: Naomi
authors.initials: N
authors.lastname: Weintrob
mesh_terms: D000293:Adolescent; D000324:Adrenocorticotropic Hormone; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D007223:Infant; D008297:Male
chemical_list: D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone