Defining normative cortisol responses to the insulin tolerance test: A comparison of Elecsys®Cort I and II assays
Authors' conclusion
Elecsys®Cort II demonstrated a lower normative cortisol response to the ITT compared with Elecsys®Cort I, and the commonly used ACTH test thresholds. These data underline the need for assay- and test-specific cut-off limits to confirm or reject adrenal insufficiency.
Study context
- Population
- Healthy participants undergoing an insulin tolerance test (ITT) after an overnight fast
- Participants
- 90 participants
- Comparison
- Elecsys®Cort I vs Elecsys®Cort II assays for cortisol response to the ITT
- Outcome
- Normative cortisol cut-off to the ITT: 2.5th percentile of peak cortisol for each assay
Main finding
As reported in the abstract
2.5th percentile of peak cortisol (normative cut-off)
Further findings
Peak cortisol
5th percentile of peak cortisol
False-positive rate: healthy participants with peak cortisol below ACTH test cut-offs (500 nmol/L Cort I; 420 nmol/L Cort II)
Original publication
Defining normative cortisol responses to the insulin tolerance test: A comparison of Elecsys®Cort I and II assays. Pituitary. Published 1 December 2025. doi:10.
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