Clinical and pharmacological determinants of serum dexamethasone concentrations during dexamethasone suppression test
Authors' conclusion
Age and BMI emerged as determinants of dexamethasone exposure during 1-mg DST, while the impact of renal function and medications appears limited after adjustment.
Study context
- Population
- Patients undergoing 1-mg overnight DST with measurement of serum cortisol and dexamethasone levels
- Participants
- 546 patients
- Outcome
- Determinants of serum dexamethasone levels during 1-mg DST and their impact on test interpretation
Main finding
As reported in the abstract
Determinants of serum dexamethasone levels (multivariable linear regression)
Median dexamethasone concentration
11.9 nmol/L
Age independently associated with higher dexamethasone levels (β, p<0.001)
0.24
BMI independently associated with higher dexamethasone levels (β, p=0.010)
0.17
Observational data: associations, not effects.
Further findings
Concomitant medications (PPIs, statins, calcium channel blockers)
- Associated with higher dexamethasone levels in univariable analyses, but not after sensitivity analyses
Age-stratified models
- <65 years: BMI and PPI use associated with dexamethasone
- ≥65 years: statins and PPIs were determinants
Excluding patients with mild autonomous cortisol secretion
- BMI and eGFR remained significant
Suboptimal dexamethasone exposure (<4.5 nmol/L)
- Proportion of patients with suboptimal exposure; frequently associated with inadequate cortisol suppression
- 3.3%
Original publication
Clinical and pharmacological determinants of serum dexamethasone concentrations during dexamethasone suppression test. J Clin Endocrinol Metab. Published 8 September 2026. doi:10.
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