Does subclinical hypercortisolism adversely affect the bone mineral density of patients with adrenal incidentalomas?

OBJECTIVE Subclinical hypercortisolism (SH) is detected increasingly in a substantial proportion of patients with incidentally discovered adrenal adenomas. The clinical implications of SH are currently unclear. Osteoporosis is a well-known complication of glucocorticoid excess. So far, the impact of SH on bone mineral density (BMD) has been studied in a limited number of reports with discordant results. In the present study we evaluated the BMD in a large cohort of post-menopausal women with adrenal incidentalomas. PATIENTS AND MEASUREMENTS Forty-two post-menopausal women with incidentally discovered adrenal masses and radiological features highly suggestive of benign adrenal adenomas were investigated. All patients underwent a standard low-dose dexamethasone suppression test (LDDST; 0.5 mg 6-hourly for 2 days). The diagnosis of subclinical hypercortisolism (SH) was based on post-LDDST cortisol concentrations of >70 nmol/l. According to this criterion patients were subdivided into two groups: with (n = 18; group A) or without (n = 24; group B) SH. There was no significant difference in age, years since menopause and body mass index between these groups. BMD was measured at L2-L4 vertebrae and three sites of the proximal femur by the dual energy X-ray absorptiometry (DEXA) method. RESULTS Post-menopausal women with SH (group A) exhibited slightly but significantly lower absolute and age-adjusted BMD values compared to group B patients in the femoral neck (BMD g/cm(2): 0.72 +/- 0.08 vs. 0.79 +/- 0.09; Z -score: -0.20 +/- 0.82 vs. +0.43 +/- 0.94, P < 0.05) and trochanter (BMD g/cm(2): 0.60 +/- 0.09 vs. 0.69 +/- 0.10; Z-score: -0.32 +/- 1.0 vs. +0.30 +/- 1.05, P < 0.01). BMD measurements of the Ward's triangle were also lower in group A patients but the difference did not reach statistical significance (BMD g/cm(2): 0.60 +/- 0.10 vs. 0.68 +/- 0.13, P = 0.06). There was no difference in the lumbar vertebrae between the two groups (BMD g/cm(2): 0.888 +/- 0.13 vs. 0.90 +/- 0.16, P = 0.78; z-score: +0.50 +/- 1.16 vs. +0.11 +/- 1.5, P = 0.36). The number of patients in the osteoporotic range was minimal with no significant difference between the two groups. However, the frequency of osteopenia in group A was significantly greater than in group B patients in the trochanter and Ward's triangle areas. Serum osteocalcin (BGP) levels were significantly lower in group A compared to group B patients (18.6 +/- 8.6 vs. 26.2 +/- 8.1 ng/ml, P < 0.01); no difference existed regarding parathyroid hormone (PTH) concentrations (43 +/- 15.6 vs. 41.2 +/- 14.8 pg/ml, P = 0.72). CONCLUSIONS In this series, post-menopausal women with subclinical hypercortisolism had lower absolute and age-adjusted BMD values and a higher rate of osteopaenia in the trabecular loaded and mixed cortical-trabecular bone of proximal femur. These data demonstrate that the subtle hypercortisolism of patients with adrenal incidentalomas may have an adverse effect on the bone mass of these patients.