Reliability of the low dose synacthen test in children undergoing pituitary function testing.
BACKGROUND
There are few data in the paediatric literature on the normal cortisol response to stimulation during the low dose synacthen test (LDST) (1 microg).


OBJECTIVE
To examine the cortisol responses in children, subsequently presumed to be normal, who had an LDST during anterior pituitary function tests (APFTs).


METHODS
A retrospective review of results in children with short stature and normal growth hormone levels.


RESULTS
Of 33 children tested, seven had suboptimal cortisol responses based on accepted criteria (peak <500 nmol/l)--a false positive rate of 21%. Only three of these children had a repeat LDST, which was normal in all cases. The peak cortisol response (median 633, range, 417-1052 nmol/l) was inversely correlated with age (r = -0.44, p < 0.05).


CONCLUSIONS
One in five tests did not meet normal criteria. This false positive rate (21%) should be borne in mind when interpreting synacthen tests to prevent overdiagnosis of adrenal insufficiency.
Mushtaq
T
T
Sheffield Children's Hospital, University of Sheffield, Sheffield, UK.
Shakur
F
F
Wales
J K
JK
Wright
N P
NP
D000293:Adolescent; D000309:Adrenal Insufficiency / Q000097:blood / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D003366:Cosyntropin; D004305:Dose-Response Relationship, Drug; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood*; D008297:Male; D010901:Pituitary Function Tests / Q000379:methods*; D010903:Pituitary Gland, Anterior / Q000502:physiology*; D015203:Reproducibility of Results; D012189:Retrospective Studies
D003366:Cosyntropin; C006418:adrenocorticotropin zinc; D006854:Hydrocortisone