Evolving Treatment Paradigms in Hypercortisolism: Integrating Emerging Evidence into Practice - Episode 3
Integrating the Dexamethasone Suppression Test Into Diabetes Practice
Panelists discuss how the 1-mg dexamethasone suppression test has become the simple, first-line screening tool for hypercortisolism, replacing more complex tests such as salivary cortisol or 24-hour urine collections, with practical tips for implementation and patient education.
Video content above is prompted by the following:
The dexamethasone suppression test emerges as the gold standard screening tool for hypercortisolism in diabetes practice, replacing more complex testing methods. Vivian Fonseca, MD, FRCP, describes the straightforward protocol: Patients take 1 mg dexamethasone at bedtime and have blood drawn early the next morning for both cortisol and dexamethasone levels. The ability to measure dexamethasone levels ensures patient adherence and proper drug absorption, addressing previous concerns about test reliability. This approach has replaced urinary-free cortisol and late-night salivary cortisol testing, which showed too much variability for reliable screening.
Natalie Bellini, DNP, FNP, BC-ADM, CDCES, shares practical implementation strategies, including standardized patient handouts and Epic order sets that streamline the testing process. Patient education focuses on clear instructions: take the medication right before bed, sleep normally, and go directly to the laboratory upon waking. The practice provides reassurance about expected abnormal results, explaining that the doctors want cortisol levels to be suppressed (low numbers). Most patients can successfully complete the test with proper instruction, and the simplified protocol reduces barriers compared with previous testing methods.
Normal cortisol suppression should result in levels below 1.0 μg/dL, with the traditional cutoff of 1.8 μg/dL representing clear abnormality. Richard Auchus, MD, PhD, discusses the “gray zone” between 1.0 and 1.8 μg/dL, comparing it to prediabetes concepts where borderline values still represent increased risk. In the CATALYST study results, the mean level post dexamethasone cortisol was 3.3 μg/dL, with dexamethasone levels above 400 ng/mL, clearly indicating both adherence and significant cortisol excess. This continuum approach recognizes that hypercortisolism develops gradually and that higher cortisol levels correlate with more comorbidities and treatment difficulty.
