Objectives: The multisystem involvement in cystic fibrosis (CF) patients may alter body composition and influence bone metabolism, leading to low bone minerál densi-ty and lean body mass depletion. Peripheral quantitative computed tomography (pQCT) allows assessment of volumetric bone minerál density and assessment of the relationship between bones and muscles. Methods: This study was conducted in 80 CF patients (aged 4.5-44.9 years, 36 fema-le, 73% <18 years). Using pQCT, trabecular bone minerál density (TBD) in distal rádius, cortical bone minerál density in proximal rádius (CBD) and cross-section areas (CSA) of bone components and muscles in proximal forearm of the nondominant side were measured. Results: Weight, height and BMI of the patients were lower than in the normál popu-lation (mean SDS -1.13, -0.99 and -0.89, respectively, p<0.0001). TBD was not lower than normál (mean SDS 0.43, p = 0.064), CBD was higher than normál (mean value of SDS 0.38, p = 0.005). Cortical bone CSA and cortical thiekness were small for age (mean value of SDS -0.95 and -0.93, p = <0.0001), but cortical bone CSA was appropriate for proximal forearm muscle CSA. Proximal forearm muscle CSA was smaller than both height-matched and age-matched references (mean value of SDS -1.84 and -1.41, p <0.0001 and <0.001, respectively). Conclusions: The thinner cortical bone found in CF patients may be due to their lower muscle mass. Changes in bone minerál density in CF háve to be evaluated with caution.

        Key words: cystic fibrosis, bone minerál density, osteoporosis, pQCT