Related Experiment Video
Updated: Mar 6, 2026
Cortisol Measurement in Koala Phascolarctos cinereus Fur
Published on: August 23, 2019
Cortisol assays across the physiologic spectrum: access immunoassay compared with LC-MS/MS
Andrew J Newman1, Sanan Mahrokhian1, Isabelle Hanna1
1Center for Adrenal Disorders, Division of Endocrinology, Diabetes, and Metabolism, Mass General Brigham, Harvard Medical School, Boston, MA 02115, United States.
Insights
This study demonstrates that the Access Cortisol immunoassay closely correlates with the gold-standard liquid chromatography-tandem mass spectrometry (LC-MS/MS) for measuring serum cortisol levels across a wide physiologic range.
Area of Science:
- Endocrinology
- Clinical Chemistry
- Assay Development
Background:
- Cortisol immunoassays are widely used for adrenal function testing.
- Previous studies have not comprehensively validated immunoassay performance against LC-MS/MS across the full spectrum of cortisol production.
Purpose of the Study:
- To compare the performance of the Access Cortisol immunoassay with LC-MS/MS for serum cortisol measurement.
- To assess immunoassay accuracy across morning, post-dexamethasone suppression, and post-cosyntropin stimulation conditions.
Main Methods:
- A cross-sectional study involving 97 adults without adrenal disease.
- Serum cortisol was measured using the Access Cortisol immunoassay and LC-MS/MS at three time points.
- Analysis included correlation and concordance assessments using common clinical cutoffs.
Main Results:
- The Access Cortisol immunoassay showed good correlation with LC-MS/MS across the physiologic spectrum.
- Agreement was closer at lower cortisol levels (post-dexamethasone suppression) than at higher levels (post-cosyntropin stimulation).
- High concordance (Cohen's κ > 0.89) was observed using standard interpretative cutoffs for all conditions.
Conclusions:
- The Access Cortisol immunoassay provides reliable cortisol measurements comparable to LC-MS/MS.
- Clinicians can be confident in using this immunoassay for evaluating adrenal function across varying cortisol levels.
Background:
Immunoassays for cortisol are commonly used to evaluate adrenal function, but their similarity to gold-standard liquid chromatography-tandem mass spectrometry (LC-MS/MS) has not been demonstrated across the physiologic spectrum of cortisol production.
Methods:
In this cross-sectional study, 97 adults without known adrenal disease underwent measurements of serum cortisol in the morning, post-dexamethasone suppression, and post-cosyntropin stimulation. Samples were analyzed on the Access Cortisol immunoassay and by LC-MS/MS.
Results:
The assays showed good correlation across the physiologic spectrum, with close agreement at the lower end (mean bias -0.06 µg/dL [-1.7 nmol/L] post-dexamethasone suppression) and somewhat poorer agreement at the upper end of the physiologic spectrum (mean bias -1.68 µg/dL [-46.4 nmol/L] post-cosyntropin stimulation). Concordance using common interpretative cutoffs was good, with Cohen's κ = 0.93 for cortisol >10 µg/dL (275.9 nmol/L; morning), κ = 0.98 for cortisol <1.8 µg/dL (50 nmol/L; post-dexamethasone), and κ=0.89 for cortisol >14.5 µg/dL (400 nmol/L; post-cosyntropin).
Conclusions:
Clinicians should be reassured that this immunoassay provides cortisol measurements similar to gold-standard LC-MS/MS across the physiologic continuum.
Related Concept Videos
01:21Mass Spectrometry: Complex Analysis
GC–MS is a powerful hyphenated method commonly used in forensics and environmental...
01:33Enzyme-Linked Immunosorbent Assay
There are many different types of ELISAs, but they all involve an antibody molecule whose constant region binds an enzyme, leaving the variable region free to bind its specific antigen. Enzyme-substrate reaction allows the antigen to be visualized or...