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Evaluating the Low-Dose ACTH Stimulation Test in Children: Ideal Times for Cortisol Measurement

Harpreet Gill1, Nick Barrowman2, Richard Webster2

  • 1Department of Pediatrics, Division of Endocrinology, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada.

The Journal of Clinical Endocrinology and Metabolism
|June 21, 2019
PubMed

Insights

Testing cortisol at 15 and 60 minutes during the low-dose ACTH stimulation test (LDST) helps prevent false positive diagnoses of adrenal insufficiency (AI) in children. This approach refines timing for accurate AI diagnosis.

Area of Science:

  • Pediatric Endocrinology
  • Endocrinology
  • Clinical Chemistry

Background:

  • Central adrenal insufficiency (AI) diagnosis relies on the low-dose ACTH stimulation test (LDST).
  • Current LDST protocols often use a 30-minute cortisol sampling time, but optimal timing remains debated.

Purpose of the Study:

  • To identify optimal cortisol sampling times during the LDST in pediatric patients.
  • To determine factors that predict the timing of peak cortisol levels in children undergoing LDST.

Main Methods:

  • Retrospective chart review of LDSTs conducted between February 2014 and September 2017.
  • Cortisol levels were measured at 0, 15, 30, and 60 minutes post-cosyntropin (1 μg) administration.
  • Adrenal insufficiency was defined by cortisol values <18 μg/dL (500 nmol/L).

Main Results:

  • Peak cortisol levels occurred at 15 minutes (19%), 30 minutes (67%), and 60 minutes (14%) in 221 pediatric patients.
  • Testing at 15 or 60 minutes in addition to 30 minutes could prevent false positive LDST results.
  • Omitting 15- and 60-minute samples would have misdiagnosed 9.8% of patients who passed the LDST.

Conclusions:

  • While most children peak at 30 minutes, including 15- and 60-minute cortisol measurements reduces the risk of false positive LDST results.
  • Glucocorticoid exposure, age, and BMI z-scores are independent predictors of peak cortisol timing.
Abstract

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