Cortisol assays across the physiologic spectrum: access immunoassay compared with LC-MS/MS
Authors' conclusion
Clinicians should be reassured that this immunoassay provides cortisol measurements similar to gold-standard LC-MS/MS across the physiologic continuum.
Study context
- Population
- Adults without known adrenal disease; serum cortisol measured in the morning, post-dexamethasone suppression and post-cosyntropin stimulation
- Participants
- 97 adults
- Exposure
- Access Cortisol immunoassay vs LC-MS/MS
- Outcome
- Agreement between assays
Main finding
As reported in the abstract
Mean bias
−0.06 µg/dL
post-dexamethasone suppression; −1.7 nmol/L
Mean bias
−1.68 µg/dL
post-cosyntropin stimulation; −46.4 nmol/L
Observational data: associations, not effects.
Further findings
Concordance at common interpretative cutoffs
- Cohen's κ, cortisol >10 µg/dL (275.9 nmol/L; morning)
- 0.93
- Cohen's κ, cortisol <1.8 µg/dL (50 nmol/L; post-dexamethasone)
- 0.98
- Cohen's κ, cortisol >14.5 µg/dL (400 nmol/L; post-cosyntropin)
- 0.89
Original publication
Cortisol assays across the physiologic spectrum: access immunoassay compared with LC-MS/MS. Eur J Endocrinol. Published 5 March 2026. doi:10.
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