The risk factors for fractures and trabecular bone-score value in patients with endogenous Cushing’s syndrome

• Published in: Archives of osteoporosis Vol. 10; no. 1; p. 44
• Main Authors: Belaya, Zhanna E., Hans, Didier, Rozhinskaya, Liudmila Y., Dragunova, Natalia V., Sasonova, Natalia I., Solodovnikov, Alexander G., Tsoriev, Timur T., Dzeranova, Larisa K., Melnichenko, Galina A., Dedov, Ivan I.
• Format: Journal Article
• Language: English
• Published: London Springer London 2015
• Subjects: Absorptiometry, Photon; Adult; Area Under Curve; Bone Density - physiology; Cohort Studies; Cushing Syndrome - complications; Cushing Syndrome - diagnostic imaging; Cushing Syndrome - physiopathology; Endocrinology; Female; France; Humans; Hydrocortisone - urine; Male; Medicine; Medicine & Public Health; Original Article; Orthopedics; Osteoporotic Fractures - diagnostic imaging; Osteoporotic Fractures - etiology; Osteoporotic Fractures - physiopathology; Retrospective Studies; Risk Factors; Spinal Fractures - diagnostic imaging; Spinal Fractures - etiology; Spine - diagnostic imaging; Glucocorticoid-induced osteoporosis; Cushing’s syndrome; Fracture; Trabecular bone score; Twenty-four-hour urinary free cortisol
• ISSN: 1862-3522; 1862-3514
• DOI: 10.1007/s11657-015-0244-1

Summary
In a cohort study of 182 consecutive patients with active endogenous Cushing’s syndrome, the only predictor of fracture occurrence after adjustment for age, gender bone mineral density (BMD) and trabecular bone score (TBS) was 24-h urinary free cortisol (24hUFC) levels with a threshold of 1472 nmol/24 h (odds ratio, 3.00 (95 % confidence interval (CI), 1.52–5.92);
p
 = 0.002).
Introduction
The aim was to estimate the risk factors for fracture in subjects with endogenous Cushing’s syndrome (CS) and to evaluate the value of the TBS in these patients.
Methods
All enrolled patients with CS (
n
 = 182) were interviewed in relation to low-traumatic fractures and underwent lateral X-ray imaging from T4 to L5. BMD measurements were performed using a DXA Prodigy device (GEHC Lunar, Madison, Wisconsin, USA). The TBS was derived retrospectively from existing BMD scans, blinded to clinical outcome, using TBS iNsight software v2.1 (Medimaps, Merignac, France). Urinary free cortisol (24hUFC) was measured by immunochemiluminescence assay (reference range, 60–413 nmol/24 h).
Results
Among enrolled patients with CS (149 females; 33 males; mean age, 37.8 years (95 % confidence interval, 34.2–39.1); 24hUFC, 2370 nmol/24 h (2087–2632), fractures were confirmed in 81 (44.5 %) patients, with 70 suffering from vertebral fractures, which were multiple in 53 cases; 24 patients reported non-vertebral fractures. The mean spine TBS was 1.207 (1.187–1.228), and TBS
Z
-score was −1.86 (−2.07 to −1.65); area under the curve (AUC) was used to predict fracture (mean spine TBS) = 0.548 (95 % CI, 0.454–0.641)). In the final regression model, the only predictor of fracture occurrence was 24hUFC levels (
p
 = 0.001), with an increase of 1.041 (95 % CI, 1.019–1.063), calculated for every 100 nmol/24-h cortisol elevation (AUC (24hUFC) = 0.705 (95 % CI, 0.629–0.782)).
Conclusions
Young patients with CS have a low TBS. However, the only predictor of low traumatic fracture is the severity of the disease itself, indicated by high 24hUFC levels.