Endocrine Abstracts

Background: Osteoporosis and increased fracture risk associated with cystic fibrosis (CF) are becoming more relevant with improved life expectancy in this disease. The evolution of CF-related bone disease remains unclear.

Aims: To evaluate change in bone mineral density (BMD) in individuals with CF from age 10 to 30 y.

Methods: Data from the UK CF Trust registry, which contains anonymised clinical information, was used to evaluate BMD at age 10, 18 and 30 y against the population mean. BMD z score was adjusted for size by including height z score in linear regressions. Association of BMD with lung function (FEV1%) was evaluated.

Results: Data was available for total body (TB) BMD at 10y n=62 (30 male) and 18 y n=78 (41 male); for lumbar spine (LS) BMD at 10y n=75 (37 male), 18 y n=148 (77 male), 30y n=133 (72 male). Mean TB BMD z scores at 10y and 18 y were −0.135 and −0.921 respectively. In a one-sample t test against the population mean, TB BMD z score was significantly different at 18 y (P<0.01) but not at 10 y. There was a significant relationship between BMD z score and FEV1% at 18 y (P<0.01) but not at 10 y. Mean LS BMD z score at 10 y, 18 y and 30 y were −0.167 (P>0.05), −0.958 (P<0.01) and −0.874 (P<0.01) respectively, P values representing significant difference to the population mean. There was a significant relationship between LS BMD z score and FEV1% at 18 y (P<0.01) and 30 y (P<0.05) but not at 10 y. For the TB BMD cohort, the percentage with a BMD z score of <−2 was 3.23% at 10 y and 25.6% at 18 y; for the LS BMD cohort, this was 2.67%, 20.3% and 21.8% at 10 y, 18 y and 30 y respectively.

Conclusions: There was a trend to decreasing BMD with increasing age in individuals with CF. A relationship between reduced FEV1% and reduced BMD was observed in adulthood. These results highlight the importance of monitoring BMDin CF.