Alternative cutoffs for cortisol post-Dexamethasone suppression testing: is there a practical point for the bone health evaluation?

BACKGROUND: Current guideline-based stratification in the non-secretory adrenal tumors (ADTs) involves the second-day (post-Dexamethasone testing) plasma cortisol (D-C) threshold of <1.8 μg∕dL to determine a non-functional profile and another one for a mild cortisol secretion (cortisol between 1.8 and 5 μg∕dL). OBJECTIVE: To analyze the bone status in terms of mineral metabolism, circulating biomarkers of bone turnover and bone mineral density in menopausal women with ADTs by comparing two population subgroups, according to distinct thresholds for D-C, which are out of the current guidelines (1.4 μg∕dL and 0.9 μg∕dL, respectively). PATIENTS, MATERIALS AND METHODS: A retrospective analysis was conducted in ADT-positive menopausal women. RESULTS: Final analysis included 109 adults: ADT-1 group (52.3%; D-C: ≤1.4 μg∕dL) vs. ADT-2 group (47.7%; D-C: 1.4-5 μg∕dL) and ADT-3 group (20.2%; D-C: ≤0.9 μg∕dL) vs. ADT-4 group (79.8%; D-C: 0.9-5 μg∕dL), respectively. ADT-1 group vs. ADT-2 group was at similar age (60.14±8.56 vs. 60.08±11.85 years), menopause duration (13.85±7.41 vs. 14.19±8.54 years), body mass index (30.78±6.20 vs. 29.23±6.73 kg∕m²), and obesity rate (56% vs. 35.9%). Mineral metabolism assays showed no between-group difference. Both groups experienced a vitamin D deficiency according to 25-hydroxyvitamin D (23.69±10.42 vs. 25.35±9.98 ng∕mL, p=0.481). Except for femoral neck T-score within ADT-1 group (-1.22±1.11), all the other dual energy X-ray absorptiometry (DXA) categories were normal. The prevalence of osteoporosis diagnosis was similar: 24.5% vs. 35.4%, with lower fracture rate (3.5% compared to 21.2%, p=0.005). ADT-3 group compared to ADT-4 group showed a similar bone health status. Half of patients suffered from obesity (50% vs. 46.4%, p=0.775). A borderline significance was attributed to a higher total hip T-score in ADT-3 group vs. ADT-4 group (-0.23 vs. -0.87, p=0.06), both with intra-normal values, and a lower fracture rate (0% vs. 14.9%, p=0.053). Osteoporosis diagnosis displayed a statistically significant decrease in the prevalence in ADT-3 group vs. ADT-4 group: 5.6% vs. 35.4% (p=0.042). CONCLUSIONS: Menopausal adults with D-C >0.9 μg∕dL should be mandatory tested for osteoporosis, and those with D-C >1.4 μg∕dL should be additionally screened for osteoporotic fractures, while age is not different among the subgroups with different cutoffs.