INTRODUCTION
Bronchiectasis is a condition characterized by irreversible abnormal
dilation and anatomic breakdown of the bronchial tree. Although the
frequency pf bronchiectasis has been declining due to the improvement in
nutrition and sanitation circumstances, increased rate of vaccination
and early and frequent use of antibiotics, it still causes a serious
health problem in developing countries (1,2). Pifferi et al. reported
the frequency of bronchiectasis as 1/6000 in general pediatric
population in their study in 2004 (3).
The most common cause of bronchiectasis in developed countries is Cystic
Fibrosis (CF). Bronchiectatic patients with CF and noncystic fibrosis
have many common features. Chronic and recurrent lung infections,
chronic inflammation, inhaled corticosteroid use in inactivity and acute
exacerbations, bronchial hyperreactivity and nutritional problems are
the characteristic features of both groups of diseases (4).
Osteoporosis and osteopenia were reported to be more frequent in
patients diagnosed with CF and noncystic fibrosis bronchiectasis
compared to normal population and the frequency was reported to increase
with increasing age (4-5).
Osteoporosis is a systemic bone disease characterized with decreased
bone mineral density (BMD) and impairment of inner architecture. The
amount of mineralization is normal in all forms of osteoporosis, while
decreased bone volume in especially trabecular bone and decreased
trabecular bone cycle is noticed. Osteoporosis is evaluated using BMD,
dual-energy X-ray absorptiometry (DEXA), quantitative computed
tomography (QCT) and quantitative ultrasonography (QUS). Osteoporosis is
frequently encountered in chronic diseases, especially with long
hospital stay, inadequate vitamin D intake and drug use. Vitamin K and D
deficiency in cystic fibrosis is thought to be associated with
osteoporosis (6).
Many mechanisms are responsible in the development of osteoporosis. Bone
resorption secondary to the changes in RANK-RANKL-OPG system is in the
forefront recently (7). OPG is a member of the receptor TNFR super
family, and is also known as TNFRS11B. Another name of it is
osteoclastogenesis inhibitory factor (OCIF). Original OPG molecule is a
polypeptide composed of 401 amino acids, and the mature protein composed
of 380 amino acids is formed by separation of the 21-amino acid
propeptide part.
The association between osteoporosis and RANKL/OPG levels has been
demonstrated in the literature in patients with CF in whom
bronchiectasis is common. However, no study has been published
evaluating the association between osteoporosis and RANKL/OPG levels in
patients with noncystic fibrosis bronchiectasis. The aim of this study
was to measure the RANKL and OPG levels in patients with noncystic
fibrosis bronchiectasis and with osteoporosis. And to evaluate the
applicability of using RANKL and OPG levels as markers in the early
diagnosis of osteoporosis and its follow-up.