Nutritional status is a major determinant of bone mass in children and adolescents with cystic fibrosis, even if normal height is maintained, the largest longitudinal study to date reveals.

The New Zealand study of 60 young people with CF aged between 6 to 18 years, 40 of whom were involved in the longitudinal study,  found a positive correlation between changes in body mass index (BMI) and bone mineral density (BMD) measured at the lumbar spine.

According to the authors the findings underscore the importance of aggressive measures to improve nutrition in these patients.

While the majority of patients whose BMI centile declined over time also failed to accumulate bone, those who had improvements in BMI over time tended to have an increase in bone density across sequential scans.

This finding suggested that “impaired bone accrual is not an inevitable phenomenon,” the study authors noted in their paper published in the Journal of Clinical Endocrinology and Metabolism.

The research team also found a link between change in lung function (Fev1) with changes in BMI and BMD, “indicating that patients with declining lung function are likely to be thinner and to have lower bone mass,” the researchers wrote.

 “To our knowledge this is the longest longitudinal study assessing bone density in children and adolescents with CF… the long duration enables us to see a clear pattern: bone accrual is impaired in the sickest young people with CF, even if linear growth is minimally affected,” the study authors said.

“Measures to optimize and maintain nutritional status and lung function, especially through adolescence, should help reduce the prevalence of low bone mineral density of fractures,” they concluded.