Postmenopausal Canarian women receiving oral glucocorticoids have an increased prevalence of vertebral fractures and low values of bone mineral density measured by quantitative computer tomography and dual X-ray absorptiometry, without significant changes in parathyroid hormone

Abstract

Background: Daily doses higher than 7.5 mg/daily of prednisone or equivalents confer a great risk of vertebral and hip fractures with a clear dose dependence of fracture risk. Information regarding the utility in assessing trabecular bone mineral density by quantitative computer tomography (QCT) in these patients, either in the Canaries or in Spain, is lacking. Moreover, in this setting, the importance of secondary hyperparathyroidism is still controversial.Design, patients and methods: Cross-sectional observational study performed on 1177 consecutive Canary postmenopausal women who attended our Bone Metabolic Unit. The Patient Group was composed of 88 postmenopausal women who were taking oral corticosteroids in dose higher than 7.5 mg/day of prednisone or equivalent for more than 6 months (OG group). The Control Group included 838 postmenopausal women who did not take steroids. A complete validated questionnaire for osteoporosis risk assessment and a complete physical examination were performed. A lateral X-ray of the spine was performed on every woman. Bone mineral density (BMD) was measured at the lumbar spine (LS) by dual X-ray Absorptiometry (DXA) and QCT and at the femoral neck by DXA. Fasting serum and 24 hour urine was collected and biochemical markers of bone remodelling were studied.Results: Both groups were comparable in general characteristics and calcium intake. The OG group showed lower values of BMD estimated both by DXA and QCT (p<0.05). LS BMD was closely correlated by using both methods (r=0.636, p<0.001). The OG group showed lower values of osteocalcin (p=0.023) and TRAP (p=0.026) without significant differences in PTH. Patients in OG group had a higher prevalence of vertebral fractures than controls (13.3% vs 8.6%; crude values: p = 0.049, OR: 1.63 (0.99-2.67); age adjusted: p = 0.003, OR 2.29 (1.33-9.93)).Conclusions: In postmenopausal Canarian women, chronic glucocorticoid therapy is associated with low bone mineral density, measured either by DXA or QCT, with evidence of low turnover and high prevalence of fractures without significant changes in PTH. DXA and QCT provide similar information in the assessment of this high risk population.