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Osteoporosis in cystic fibrosis : pathogenesis and clinical features Frangolias, Despina Daisy
Objectives: Advances in the treatment of cystic fibrosis (CF) have lead to increased longevity and with it increased risk for a new set of complications including increased risk for osteoporosis. The purpose of the study was to elucidate the prevalence of low bone mineral density (BMD) in an adult CF population with heterogeneous severity of pulmonary disease and to ascertain clinical and laboratory correlates of low BMD. Methodology: The study design was a cross sectional investigation of BMD at one adult CF clinic. We measured spinal (Ll-4) and femoral BMD by dual energy x-ray absorptiometry (DEXA) in 68 (24 female) CF adults aged 18-55 years. The BMD standard scores for spine and femoral neck were averaged and the composite score used for analyses. Differences in disease severity, exercise capacity and physical activity level, dietary intake, body composition and body mass index, bone turnover, pubertal status, glucocorticoid use, vertebral and non-vertebral fracture rate, and back pain were investigated for associations with changes in BMD. Results: Out of our sample of 68 patients tested, we identified 58 patients with low BMD with 9 patients classified as osteoporotic. Low BMD was associated with declining pulmonary function and increasing age. Late diagnosis of CF was associated with low BMD in adulthood. Multiple regression analysis identified exercise capacity and body mass index as the most significant variables predicting changes in BMD. Current dietary intake was not predictive of present BMD, however inadequate intakes of calcium and vitamin D were documented. Body composition was moderately associated with BMD. Onset of puberty was delayed in those who showed decreased BMD in adulthood. Kyphosis and back pain were not predictive of low spinal BMD. Conclusions: Low BMD is common in adult CF patients. Increased severity of pulmonary disease, poor exercise tolerance and inadequate weight gain contribute to BMD deficits in adulthood. Delayed diagnosis of CF also contributes to low BMD in adulthood. Several other clinical and nutritional factors contribute to BMD deficits.
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