Abstract
ObjectiveTo evaluate the cut-off value of the ratio of 24 h urinary free cortisol (24 h UFC) levels post-dexamethasone to prior-dexamethasone in dexamethasone suppression test (DST) during the diagnosis of primary pigmented nodular adrenocortical disease in Chinese adrenocorticotropic hormone-independent Cushing syndrome.DesignRetrospective study.ParticipantsThe patients diagnosed with primary pigmented nodular adrenocortical disease (PPNAD, n = 25), bilateral macronodular adrenal hyperplasia (BMAH, n = 27), and adrenocortical adenoma (ADA, n = 84) were admitted to the Peking Union Medical College Hospital from 2001 to 2016.EstimationsSerum cortisol, adrenocorticotropic hormone (ACTH), and 24 h UFC were measured before and after low-dose dexamethasone suppression test (LDDST) and high-dose dexamethasone suppression test (HDDST).ResultsAfter LDDST and HDDST, 24 h UFC elevated in patients with PPNAD (paired t-test, P = 0.007 and P = 0.001), while it remained unchanged in the BMAH group (paired t-test, P = 0.471 and P = 0.414) and decreased in the ADA group (paired t-test, P = 0.002 and P = 0.004). The 24 h UFC level after LDDST was higher in PPNAD and BMAH as compared to ADA (P < 0.017), while no significant difference was observed between PPNAD and BMAH. After HDDST, 24 h UFC was higher in patients with PPNAD as compared to that of ADA and BMAH (P < 0.017). The cut-off value of 24 h UFC (Post-L-Dex)/(Pre-L-Dex) was 1.16 with 64.0% sensitivity and 77.9% specificity, and the cut-off value of 24 h UFC (Post-H-Dex)/(Pre-H-Dex) was 1.08 with 84.0% sensitivity and 75.6% specificity.ConclusionThe ratio of post-dexamethasone to prior-dexamethasone had a unique advantage in distinguishing PPNAD from BMAH and ADA.
Highlights
Cushing syndrome (CS) is characterized by chronic exposure to excessive glucocorticoid, and classified into adrenocorticotropic hormone (ACTH)-dependent and ACTH-independent CS
After low-dose dexamethasone suppression test (LDDST) and high-dose dexamethasone suppression test (HDDST), 24 h urinary free cortisol (UFC) elevated in patients with primary pigmented nodular adrenal disease (PPNAD), while it remained unchanged in the bilateral macronodular adrenal hyperplasia (BMAH) group and decreased in the
The ratio of post-dexamethasone to priordexamethasone had a unique advantage in distinguishing PPNAD from BMAH and ADA
Summary
Cushing syndrome (CS) is characterized by chronic exposure to excessive glucocorticoid, and classified into adrenocorticotropic hormone (ACTH)-dependent and ACTH-independent CS. ACTH-independent CS accounts for approximately 15–20% of CS, primarily due to the unilateral adrenal tumor such as adrenocortical adenoma (ADA) and adrenal carcinoma that accounts for 10 and 5%, respectively. The rare causes of ACTH-independent CS include primary bilateral macronodular adrenal hyperplasia (BMAH), primary pigmented nodular adrenal disease (PPNAD), and McCune–Albright syndrome [1]. PPNAD is rarely encountered and accounts for 0.6–1.9% of CS [2]. It can occur isolated or as a component of the Carney complex (CNC).
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