Growth Hormone Improves Bone Mineral Content in Children with Cystic Fibrosis

Aim: Osteoporosis and osteopenia have been reported as common complications of cystic fibrosis (CF); however, little is known about accrual of bone mineral in CF. The goal of our study was to measure bone mineral content (BMC) in non-acutely-ill, but poorly growing children with CF, and to determine the relationship between height, lean body mass and BMC. Our second aim was to evaluate the effect of one year of treatment with human recombinant growth hormone (GH) on total body BMC.

Methods: We measured total-body BMC using dual energy X-ray absorptiometry in 32 poorly growing (height < or =10th percentile for age) prepubertal Caucasian children (ages 7 years 6 months-12 years 9 months, 17 M and 15, F) with CF. BMC and lean tissue mass (LTM) were measured at baseline, at 6 months and one year. One half of the children were randomly assigned to receive treatment with GH (GHTX). Results were compared to reference data maintained for healthy children matched for age and ethnicity. Sex steroid and IGF-I levels were also measured.

Results: Children with CF exhibited lower total body BMC and LTM than age-, ethnicity- and gender-matched controls. This was still apparent when the data were matched for height and bone age. BMC correlated with height, LTM, and IGF-I levels. Although at baseline the groups were similar, the GHTX group demonstrated significantly greater increase in height, weight, LTM and BMC than the NonTX group. These differences remained despite correction for increase in height

Conclusion: Our study is the first to evaluate BMC in children with CF and suggests that poor accumulation of bone mineral is a problem. We have further demonstrated that GH treatment improves accumulation of bone mineral.