Comparison of low-dose and high-dose cosyntropin stimulation testing in children.
BACKGROUND
There is no consensus among pediatric endocrinologists in using low-dose (LD) versus high-dose (HD) cosyntropin to test for secondary/tertiary adrenal insufficiency. This paper compares LD and HD cosyntropin stimulation testing in children for evaluation of hypothalamic-pituitary-adrenal axis (HPAA) and suggests a new peak cortisol cut-off value for LD stimulation testing to avoid false positivity.


METHODS
Data of 36 children receiving LD (1 µg) and HD (249 µg) cosyntropin consecutively during growth hormone (GH) stimulation testing were analyzed in two groups. Group A were patients who passed GH stimulation testing and were not on oral, inhaled or intranasal steroids (intact hypothalamic-pituitary axis, n= 19). Group B were patients who failed GH stimulation testing and/or were on oral, inhaled or intranasal steroids (impaired hypothalamic-pituitary axis, n= 17).


RESULTS
In group A, the mean peak cortisol response in LD cosyntropin was 18.5 ± 2.4 µg/dL and that for the HD cosyntropin was 24.8 ± 3.1 µg/dL (r: 0.76, P≤ 0.05). In group B, the mean peak cortisol response in LD cosyntropin was 15.7 ± 6.1 µg/dL and that for HD cosyntropin was 21.7 ± 7.9 µg/dL (r: 0.98, P≤ 0.05). When a standard cut-off of 18 µg/dL was used, 37% of the patients with intact HPAA failed LD cosyntropin testing, but a cut-off of 14 µg/dL eliminated false positive results.


CONCLUSIONS
LD cosyntropin stimulation testing results should be interpreted cautiously when used alone to prevent unnecessary long-term treatment. Using a lower cut-off for LD (≥14 µg/dL) seems to avoid false positive results and still detects most cases of impaired HPAA.
Cemeroglu
Ayse Pinar
AP
Helen DeVos Children's Hospital, Spectrum Health Medical Group, Michigan State University, Pediatric Endocrinology and Diabetes Clinic, Grand Rapids, Michigan, USA. ayse.cemeroglu@devoschildrens.org
Kleis
Lora
L
Postellon
Daniel C
DC
Wood
Michael A
MA
D000293:Adolescent; D000309:Adrenal Insufficiency / Q000175:diagnosis* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D003366:Cosyntropin / Q000008:administration & dosage*; D005189:False Positive Reactions; D005260:Female; D006728:Hormones / Q000008:administration & dosage*; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D007118:Immunoassay / Q000379:methods; D008297:Male; D010912:Pituitary-Adrenal Function Tests / Q000379:methods*; D010913:Pituitary-Adrenal System / Q000503:physiopathology; D012189:Retrospective Studies
D006728:Hormones; D003366:Cosyntropin; D006854:Hydrocortisone