Decreased bone mineral density in normal-growing patients with cystic fibrosis

Abstract

Aim: To study bone mineral density (BMD) in normal-growing patients with cystic fibrosis (CF) and its relation to clinical and biochemical markers of nutrition and lung function. Methods: Seventy consecutive patients aged 6-49 y with CF were investigated using dual X-ray absorptiometry and the findings related to anthropometric data. Energy intake was calculated and basal metabolic rate and serum values for calcium, phosphorus, calcitonin and 25(OH) calcidiol measured. Working capacity, lung function and pseudomonas colonization were determined as parameters of physical fitness and severity of pulmonary disease. Results: The average z-score of BMD was decreased in the lumbar spine in both children and adults, being -0.7 ± 1.0 and -0.5 ± 1.0, respectively, as was the femoral neck BMD z-score, being -0.3 ± 0.9 and -1.1 ± 1.0 for children and adults, respectively. BMD was correlated to lung function and working capacity, but not to anthropometric data at multiple regression analysis compensating for age and calcitonin. No correlation was found with energy intake, basal metabolic rate or biochemical markers, with the exception of calcitonin. Conclusion: BMD z-scores were significantly lower than those in the normal population despite normal anthropometry. Osteoporosis was rare. The strongest correlation was found with lung function. Our data indicate that BMD at all ages might be a sensitive indicator of the general status of patients with CF.