CRP and rheumatoid arthritis: The analysis of the relationship between selected biomarkers of both bone turnover (PINP, CTX-I and PINP/CTX-I ratio) and osteoclastogenesis (sRANKL, OPG, sRANKL/OPG ratio) as well as clinical (DAS 28-ESR) and laboratory (ESR, CRP) indicators of disease activity in RA patients at the beginning and after 15 months of anti-TNF-α therapy are presented in Table 5.