Evaluation of bone metabolism in children with cystic fibrosis

Abstract

Background: Cystic fibrosis (CF) bone disease (CFBD) has attracted considerable recent interest from researchers, although several aspects of CFBD pathophysiology remain poorly understood. The objective of this research was to investigate CFBD in children with CF and its relation to clinical and bone metabolism markers.

Methods: In a prospective observational study of 68 patients with CF and 63 healthy controls, we studied bone turnover biomarkers and bone mineral density (BMD). The biomarkers included osteocalcin, total-alkaline phosphatase, bone-alkaline phosphatase, N-terminal propeptide of type-1-procollagen, osteoprotegerin (OPG), interleukine-6, tumor necrosis factor alpha (TNF-α), type-1-collagen cross-linked C-telopeptide (CTX), parathormone (PTH), 25-vitamin D, 1,25-vitamin D, calcium and phosphorus. BMD was examined in lumbar spine, comparing two healthy Spanish populations. Two regression analyses were applied to any significant associations to evaluate predictors of BMD and of CF, expressed as odds ratios (OR) with 95% confidence intervals.

Results: After adjusting for age, sex, and height Z-score, gains in BMD LS in children and adolescents (6-16 years) with CF were not less than in healthy reference population. Patients with CF showed significant associations with different bone turnover biomarkers. Age, gender, body mass index, PTH, CTX and OPG were significant predictors of BMD (R² = 0.866, p < 0,001). Moreover, we found that PTH (OR = 1.070; 95% CI 1.019-1.123), and TNFα (OR = 2.173; 95% CI 1.514-3.118) were significantly linked to CF, and calcium (OR = 0.115; 95% CI 0.025-0.524), 1,25-vitamin D (OR = 0.979; 95% CI 0.962 0.996) and OPG (OR = 0.189; 95% CI 0.073-0.489) were significant reduced.

Conclusion: A normal bone mineral density along with altered remodeling was found in CF patients with a normal nutritional status and without acute lung disease.

Keywords: Bone mineral density; Bone turnover; Cystic fibrosis.