Decreased Bone Density in Chronic Obstructive Pulmonary Disease Patients

Objective: The clinical course of patients with chronic obstructive pulmonary disease (COPD) is often complicated by the development of systemic effects one of which is osteoporosis. The purpose of this study was to investigate potential risk factors for osteoporosis in COPD patients. Material and Methods: We conducted a cross-sectional study in 45 consecutive males with COPD recruited from the outpatient clinic. Demographic data were recorded. Pulmonary function tests [percent of predicted forced expiratory volume in 1 second (FEV1%), forced vital capacity (FVC), FEV1/FVC ratio], maximal inspiratory and expiratory pressures (MIP and MEP), arterial blood gas (ABG) analyses, endocrine tests related to bone density and bone mineral density parameters (vertebral "T" scores (VTS) and femoral "T" scores (FTS)) were performed. Patients were allocated into three groups consisting of 15 patients each, according to history of corticosteroid (CS) use: Patients who have never used any CS, subjects who have been on inhaled steroids (fluticasone dose equivalent to at least 250 mu g.day-1 propionate or 400 mu g.day-1 budesonide for at least 36 months) or systemic steroids (methylprednisolone mean dose of at least equivalent to 20mg.day-1 of for at least two weeks). Results: Three groups were not different regarding osteoporosis. However, in systemic CS group MEP and calcitonin levels were lower than those of inhaled CS group and never CS group (p<0.05 for each). VTS was positively correlated with partial arterial oxygen concentration (PaO2), arterial oxygen saturation % (SaO2) and body mass index (BMI) (r=0.44, p<0.01; r=0.49, p<0.01, r=0.34, p<0.05 respectively). FTS was only well correlated with BMI(r=0.34, p<0.05). Conclusion: Bone densities were similar into three groups. Parameters related with severity of COPD such as bronchoconstruction and hypoxemia, along with low BMI were found as risk factors in the development of osteoporosis in COPD patients. Preserved MEP and calcitonin levels in inhaled CS group suggested that respiratory muscle strength and bone resorption were not affected by inhaled CS opposite to systemic steroids.