Overnight Dexamethasone Suppression Test: Enhanced Accuracy With Late-afternoon Cortisol and Morning/Late-afternoon ACTH
Authors' conclusion
Late-afternoon cortisol measurement is a novel modification that enhances ODST specificity. ACTH measurement was particularly useful in COCP and CKD. Before widespread integration in clinical practice, further validation is required.
Study context
- Population
- Healthy adults, combined oral contraceptive pill (COCP) users, chronic kidney disease (CKD), treatment-naïve A-CS, posttreatment CD in remission or persistence; standard 1-mg dexamethasone suppression test with cortisol/ACTH at 8–9 AM and 3–4 PM
- Participants
- 60 / 29 / 29 / 33 / 23 / 31
- Comparison
- Overnight dexamethasone suppression (ODS) 4 PM cortisol and 8 AM/4 PM ACTH vs standard ODS 8 AM cortisol
- Healthy adultsn = 60
- COCPn = 29
- CKDn = 29
- A-CSn = 33
- Cushing disease in remission (CD-R)n = 23
- CD-Pn = 31
- Outcome
- Specificity of ODS cortisol (cutoff 1.8 μg/dL) and ACTH (cutoff 10 pg/mL), 8 AM and 4 PM
Methodological detailsprospective, single-centre
- Prospective
- Single-centre
Performance
As reported in the abstract
| Test or model | Sensitivity 8 AM and 4 PM ACTH | Specificity 8 AM cortisol | Specificity 4 PM cortisol | Specificity 8 AM ACTH | Specificity 4 PM ACTH |
|---|---|---|---|---|---|
| Healthy adults | — not stated in the abstract | 95% | 100% | 95% | 100% |
| COCP | — not stated in the abstract | 55% | 79% | 100% | 100% |
| CKD | — not stated in the abstract | 17% | 52% | 96.6% | 100% |
| A-CS | 100% | — not stated in the abstract | — not stated in the abstract | — not stated in the abstract | — not stated in the abstract |
Sensitivity 8 AM and 4 PM ACTH
Healthy adults— not stated in the abstract
COCP— not stated in the abstract
CKD— not stated in the abstract
A-CS100%
Specificity 8 AM cortisol
Healthy adults95%
COCP55%
CKD17%
A-CS— not stated in the abstract
Specificity 4 PM cortisol
Healthy adults100%
COCP79%
CKD52%
A-CS— not stated in the abstract
Specificity 8 AM ACTH
Healthy adults95%
COCP100%
CKD96.6%
A-CS— not stated in the abstract
Specificity 4 PM ACTH
Healthy adults100%
COCP100%
CKD100%
A-CS— not stated in the abstract
— not stated in the abstract
Further findings
| Outcome | P value |
|---|---|
| ODS 4 PM vs 8 AM cortisolHealthy adults: 4 PM vs 8 AM · lower at 4 PM | P = 0.003 |
| ODS 4 PM vs 8 AM cortisolCOCP: 4 PM vs 8 AM · lower at 4 PM | P < 0.001 |
| ODS 4 PM vs 8 AM cortisolCKD: 4 PM vs 8 AM · lower at 4 PM | P < 0.001 |
| ODS 4 PM vs 8 AM cortisolCD-R: 4 PM vs 8 AM · lower at 4 PM | P = 0.001 |
Diagnostic accuracy for differentiating CD-R from CD-P
- ODS 4 PM cortisol
- 98.1%
- ODS 8 AM ACTH
- 81.5%
- ODS 4 PM ACTH
- 81.5%
ODS 4 PM vs 8 AM cortisol
- Difference not significant in treatment-naïve A-CS and CD-P
Original publication
Overnight Dexamethasone Suppression Test: Enhanced Accuracy With Late-afternoon Cortisol and Morning/Late-afternoon ACTH. J Clin Endocrinol Metab. Published 16 September 2025. doi:10.
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