Bone quality, as measured by trabecular bone score in patients with adrenal incidentalomas with and without subclinical hypercortisolism

Abstract

Patients with adrenal incidentalomas (AIs) and subclinical hypercortisolism (SH) have increased risk of fracture independent of bone mineral density (BMD) and possibly due to reduced bone quality. The trabecular bone score (TBS) has been proposed as a index of bone microarchitecture. The aim of the study was to investigate TBS in AI. In 102 AI patients, SH was diagnosed in the presence of at least two of the following: (1) urinary free cortisol >70 mg/24 h (193.1 nmol/L); (2) cortisol after 1-mg dexamethasone suppression test (1-mg DST) >3.0 mg/dL (82.8 nmol/L); or (3) adrenocorticotropic hormone (ACTH) <10 pg/mL (<2.2 pmol/L). In patients and in 70 matched controls, BMD was measured at lumbar spine (LS) and femur (neck [FN] and total [FT]) by dual X-ray absorptiometry and TBS was assessed in the region of LS-BMD; BMD and TBS data were reported as Z-scores. In patients, vertebral deformities were assessed by radiograph. Patients with SH (n ¼ 34) had lower LS-BMD (À0.31 AE 1.17), FT-BMD (À0.29 AE 0.91), and TBS (À3.18 AE 1.21) than patients without SH (n ¼ 68, 0.31 AE 1.42, p ¼ 0.03; 0.19 AE 0.97, p ¼ 0.01; À1.70 AE 1.54, p < 0.0001, respectively) and controls (0.42 AE 1.52, p ¼ 0.02; 0.14 AE 0.76, p ¼ 0.02; À1.19 AE 0.99, p < 0.0001, respectively). TBS was inversely correlated with 1-mg DST (b ¼ À0.26, t ¼ À2.79, p ¼ 0.006) regardless of age, LS-BMD, body mass index (BMI), and gender. The presence of fracture was associated with low TBS alone (odds ratio [OR], 4.8; 95% confidence interval [CI], 1.85-12.42, p ¼ 0.001) and with the cluster low TBS plus low LS-BMD (OR, 4.37; 95% CI, 1.71-11.4, p ¼ 0.002), after adjustment for age, BMI, and gender. Low TBS plus low LS-BMD showed a good specificity (79%) for predicting fractures, whereas normal TBS (ie, > À1.5) plus normal LS-BMD high specificity (88.1%) for excluding fractures. Finally, TBS predicted the occurrence of a new fracture in 40 patients followed for 24 months (OR, 11.2; 95%CI, 1.71-71.41, p ¼ 0.012) regardless of LS-BMD, BMI, and age. In SH, bone quality, as measured by TBS, is altered. TBS is useful in detecting AI patients at risk of fractures. ß

Prevalence of subclinical contributors to low bone mineral density and/or fragility fracture

“…Indeed, this point was not assessed in the study of Tannenbaum et al (3), while in two other studies only fractured subjects were included (6,7). The presence of a fragility fracture was found to be associated with the presence of subclinical contributors to low BMD and/or fragility fracture regardless of BMD, confirming that, in these patients, BMD explains only in part the increased fracture risk (1,2,44).…”

Bilateral and unilateral adrenal incidentalomas: biochemical and clinical characteristics

“…The finding that the prevalence of spine fractures was higher but the spine BMD was comparable between the groups might be considered surprising. However, in patients with SH, and in general in subjects with secondary forms of osteoporosis, bone quality is reduced (24). Therefore, in these subjects bone density only partially explains the risk of fractures.…”

Quantitative imaging methods in osteoporosis

“…TBS is less expensive and more easily accessible than CT or MRI for wide-spread clinical implementation or as an outcome in large research studies. The very first TBS reports showed applications for the prediction of fracture risk in osteoporosis (39)(40)(41), have added value in those individuals with bone density outside of the osteoporosis range (42) and monitoring of treatment effects (43,44), and similarly, TBS may find an application in other conditions such as primary hyperparathyroidism (45), hypercortisolism (46), rheumatoid arthritis (47), and diabetes-related bone disease (48). A major advantage is that it can be derived from DXA scans using dedicated post-processing software.…”