Basal Cortisol as a Predictor of Passing Short Synacthen Test and the Utility of the 60-Minute Poststimulation Cortisol
Authors' conclusion
BC reliably predicts AS, avoiding unnecessary SST in a substantial number of patients. Adjusted thresholds for pituitary pathology and by time of day can enhance accuracy. Both 30- and 60-minute poststimulation cortisol identified a small group who would have failed SST using a single poststimulation measurement.
Study context
- Population
- Adults undergoing Short Synacthen testing (SST) (IM Synacthen 250 mcg; cortisol at baseline, 30 and 60 min) at a public tertiary pathology service (PathWest), Western Australiaof 1216 SSTs
- Participants
- 704 adults
- Comparison
- Basal cortisol thresholds for predicting adrenal sufficiency on SST
- Outcome
- BC threshold predicting adrenal sufficiency (cortisol >430 nmol/L at 30 min and/or >500 nmol/L at 60 min) with 95% specificity
Methodological detailssingle tertiary pathology service, ROC analysis
- Single tertiary pathology service
- ROC analysis
Performance
As reported in the abstract
BC threshold predicting adrenal sufficiency with 95% specificity
- Adrenal sufficiency on SST
- 571 (81%)
- Basal cortisol (BC) threshold predicting adrenal sufficiency (AS) at 30 or 60 min
- ≥335 nmol/L
- Pituitary pathology subgroup threshold (95% specificity)
- ≥240 nmol/L
- Threshold for samples collected after 0945 hours
- ≥251 nmol/L
- SSTs that could have been avoided
- 31.1%
Further findings
Passed SST solely on 60-min cortisol · 60 minutes
- Patients
- 19 (2.7%)
- Median cortisol
- 420 nmol/L
Original publication
Basal Cortisol as a Predictor of Passing Short Synacthen Test and the Utility of the 60-Minute Poststimulation Cortisol. J Clin Endocrinol Metab. Published 23 July 2025. doi:10.
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