[High prevalence of osteoporosis in adult cystic fibrosis patients]

Abstract

Background and objective: In adult patients with cystic fibrosis bone metabolism may be altered by multiple mechanisms, such as abnormal calcium homeostasis, malnutrition, chronic inflammation or inactivity in the course of respiratory failure. In contrast to the high prevalence of osteoporosis in CF patients before lung transplantation, data from different CF collectives show great variation. It was the purpose of our cross-sectional study to determine changes in bone metabolism by measuring bone mineral density, and assessing calcium metabolism and clinical characteristics in adult patients (mean age 32 years) with cystic fibrosis.

Patients and methods: Bone mineral density (quantitative digital radiography), parameters of calcium homeostasis and clinical characteristics were determined in 34 adult patients with cystic fibrosis.

Results: The mean age of the study population was 32 years (range 20 to 47; 21m: 13f). 13 patients had normal T-values (mean bone mineral density in young adults), whereas 11 patients (32 %) had osteopenia and 10 (29 %) had osteoporosis. Calcium homeostasis was abnormal in only one case. In contrast T-values were positively correlated with a low body mass index (p = 0.01) and a low one-second forced expiratory volume (FEV1) (p < 0.05).

Conclusion: Decreased mineral bone density is a frequent complication in adult patients with cystic fibrosis, but does not occur inevitably even in long-standing disease (up to 47 years). In our cohort measurable alterations of calcium homeostasis could be avoided by consistent substitution policy. The main determinants of a low T-value were poor nutritional status, lowered serum calcium or phosphate concentrations and severely impaired lung function as indicator of the progression of the disease. Screening of adult patients with CF can be recommended especially in presence of malnutrition or poor lung function.