Background

Adults with CF show a higher rate of osteoporosis compared to healthy adults. Achieving proper adult bone mass is a process starting in childhood. We aimed to evaluate the prevalence, course in time and risk factors for decreased bone mineral density (BMD) in youth with CF.

Methods

Anthropometry, Dual Energy Xray Absorptiometry (DXA) scans, and endocrine data were collected in 106 children and adolescents with CF. BMD Z-scores were adjusted for height. At risk and low BMD were defined as Z-scores ≤ -1 and ≤ -2, respectively. Multivariate analyses were performed for change in BMD in 65 patients with a second DXA scan available.

Results

At baseline, overall normal median (IQR) height-adjusted BMD z-scores were found (-0.02 (-0.85 – 0.55) and -0.01 (-0.72 – 0.82 (for lumbar spine (LS) and total body less head (TBLH) respectively). In 6.6% and 2.8% of patients low BMD values were found for LS and TBLH.

At follow-up, significant decreases in BMD at both LS and TBLH were identified (p = 0.003 and p<0.001). The decrease in TBLH BMD was higher in boys than girls (p <0.001). Female gender (β = 0.451, p = 0.001) was a positive predictor and new onset of CFRD (β = -0.453, p = 0.006) was a negative predictor for the change in TBLH BMD. 

Conclusion

Most children and adolescents with CF have normal BMD. However a significant decrease in BMD over time is already seen during childhood, especially in boys and in those with newly onset CFRD.