The Low-Dose ACTH Test Does Not Identify Mild Insufficiency of the Hypothalamic-Pituitary-Adrenal Axis in Children with Inadequate Stress Response

Objective: To investigate retrospectively the sensitivity of published cortisol cut-off points of the low-dose ACTH test (LDAT) in children with proven mild hypothalamic-pituitary-adrenal (HPA) axis insufficiency. Patients and Methods: The HPA axis of 11 pediatric patients (age range: 5.5-14.5 yr) with established mild HPA axis insufficiency was reinvestigated with the LDAT. The sensitivity of the LDAT was calculated on the basis of published stimulated cortisol cut-off points. Results: The LDAT showed both a significantly higher cortisol peak and a greater cortisol rise compared with the ITT (both P<0.01). The LDAT yielded a low sensitivity of 9-55 % using published cortisol cut-off points as references. Conclusion: Using published cortisol cut-off points, the LDAT showed a poor sensitivity to detect mild HPA axis insufficiency. We cannot recommend the use of the LDAT as a screening test of HPA axis impairment in such children.