Bone tissue metabolism in men with ankylosing spondylitis

The aim of the study was the composite estimation of bone tissue metabolism in ankylosing spondylitis (AS) after having taken into account such factors as a high risk of incidence of osteoporosis in patients with AS and potential danger of permanent immobility.

Sixty-six patients with established diagnosis of AS and 63 healthy individuals in the control group were included into the study. To measure bone mineral density (BMD) the dual energy X-ray absorptiometry (DEXA) method was used. Additionally, biochemical markers of osteoporosis such as bone fraction of an alkaline phosphatase (BALP), osteocalcin (BGP) and deoxypyridinoline (Dpd) as well as many inflammatory markers of disease activity have been determined.

In our study with AS had significantly diminished bone mineral density, as compared with health controls. The presence of osteopenia/osteoporosis was associated with longer duration of the disease and with higher age. In the overall group of AS patients bone degradation marker, Dpd, correlated with serum concentration of interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha) and C-reactive protein (CRP), and inversely with BMD measured in the forearm. However, no direct association could be revealed between lower bone density and markers of inflammation or inflammatory cytokines, except of IL-6 witch was significantly higher in AS patients with osteoporosis/osteopenia than those without.

Our results indicate that disease duration and higher age are risk factors for osteoporosis in patients with AS. Inflammation might contribute to the accelerated bone loss in AS through stimulation of bone degradation.