Bone density in children and adolescents with cystic fibrosis,☆☆,,★★

https://doi.org/10.1016/S0022-3476(96)70424-9Get rights and content

Abstract

OBJECTIVE: To assess bone mineralization in children and adolescents with cystic fibrosis. DESIGN: A cross-sectional, observational study of bone mineral density (BMD) in the lumbar vertebrae and the proximal femur of 62 patients aged 4.9 to 17.8 years (mean, 10.7 years). The age-normalized BMD findings (z scores) were correlated with multiple variables, including measures of pulmonary disease, nutritional status and growth, genotype, calcium intake, and serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels. RESULTS: The mean BMD zscore was –1.03 ± 0.14 (±SE) in the lumbar vertebrae and –0.71 ± 0.17 in the proximal femur. The BMD in this age range declined relative to normal values at a rapid rate of roughly 1 SD every 6 to 8 years. The BMD z scores correlated well with multiple measures of disease severity, particularly weight and forced expiratory volume in 1 second. CONCLUSIONS: Significant osteoporosis in adults with CF results at least in part from a failure to accumulate bone mineral at a normal rate during skeletal growth and development. The cause of this is likely multifactorial. With increasing longevity, the skeletal consequences of CF become an important consideration. (J PEDIATR 1996;128:28-34)

Section snippets

METHODS

The study was a cross-sectional, observational evaluation. All patients included in the previous study of thoracic kyphosis and fracture11 who were less than 18 years of age and returned to the University of North Carolina pediatric pulmonary outpatient clinics during the study enrollment period were invited to undergo the evaluation. The participants were 34 male and 28 female subjects ranging in age from 4.9 to 17.8 years, with a mean age of 10.7 ± 3.6 years (±SD). Informed consent approved

RESULTS

Bone density z scores decreased across the age range of 4 to 18 years, with a slope of 0.15 SD per year in the lumbar vertebrae (linear regression analysis: SE = 0.03, R2 = 0.25, p = 0.0001) and 0.13 per year in the proximal femur (SE = 0.04, R2 = 0.15, p = 0.003). Separate analyses for male and female subjects showed no significant differences (p >0.1). For the entire group, the mean BMD z score was –1.03 ± 0.14 (±SE) in the lumbar vertebrae and –0.71 ± 0.17 in the proximal femur.

Figure.

DISCUSSION

As patients with CF live longer, the effect of the disease on growth and development of the immature skeleton becomes important. Bone mineral density in the lumbar vertebrae and proximal femur, normalized for age (z scores), decreased roughly 1 SD every 6 to 8 years across the age range of 4 to 18 years. This finding is consistent with the data of others who have used dual-energy x-ray absorptiometry to study BMD in adults with CF.5, 6, 28 In contrast to our findings in children, bone mineral

Acknowledgements

We thank Debra Riggs, RT, for technical assistance with the dual-energy x-ray absorptiometry studies; Gayle Lester, PhD, of the Division of Orthopaedics research laboratories, for her help with the vitamin D assays; Julie Dickinson, MStat, and Ralph DeMasi, PhD, for the statistical analyses; and Drs. Gerald Fernald, Robert Wood, Marianna Henry, and the other members of the University of North Carolina Division of Pediatric Pulmonary Medicine for their help with this study.

References (40)

  • RC Henderson et al.

    Mineralization in children and adolescents with a milk allergy

    Bone Miner

    (1994)
  • N Vaisman et al.

    Energy expenditure of patients with cystic fibrosis

    J PEDIATR

    (1987)
  • NN Huang et al.

    Clinical features, survival rate, and prognostic factors in young adults with cystic fibrosis

    Am J Med

    (1987)
  • LM Taussig et al.

    A new prognostic score and clinical evaluation system for cystic fibrosis

    J PEDIATR

    (1973)
  • JG Hanly et al.

    Hypovitaminosis D and response to supplementation in older patients with cystic fibrosis

    Q J Med

    (1985)
  • RJ Stead et al.

    Vitamin D and parathyroid hormone and bone mineralization in adults with cystic fibrosis

    Thorax

    (1988)
  • AB Grey et al.

    Bone mineral density and body composition in adult patients with cystic fibrosis

    Thorax

    (1993)
  • EH Mischler et al.

    Demineralization in cystic fibrosis

    Arch Pediatr Adolesc Med [Am J Dis Child]

    (1979)
  • J De Schepper et al.

    Low serum bone gamma-carboxyglutamic acid protein concentrations in patients with cystic fibrosis: correlation with hormonal parameters and bone mineral density

    Horm Res

    (1993)
  • V Gilsanz et al.

    Changes in vertebral bone density in black girls and white girls during childhood and puberty

    N Engl J Med

    (1991)
  • Cited by (0)

    From the Departments of Orthopedics and Pediatrics, University of North Carolina, Chapel Hill

    ☆☆

    Supported by the General Clinical Research Center at the University of North Carolina under grant No. M01-RR00046.

    Reprint requests: Richard C. Henderson, MD, PhD, University of North Carolina, 237 Burnett-Womack Building, CB No.7055, Chapel Hill, NC 27599-7055.

    ★★

    0022-3476/96/$5.00 + 0 9/20/68474

    View full text