Background Rheumatoid arthritis (RA) is a chronic inflammatory disease that results in localized and generalized bone loss. Osteoporosis and anemia are one of the most common complications seen in patients with RA.
Objectives The aim of this study was to identify the relationship between inflammation, hemoglobin, BMD loss and fibroblast growth factor (FGF)-23 that is a phosphaturic hormone.
Methods This study included 42 patients with rheumatoid arthritis fulfilling the new American college of Rheumatology/European League Against Rheumatism diagnostic criteria for rheumatoid arthritis and 26 healthy volunteers as controls. All were subjected to a complete blood count, rheumatoid factor and/or anti-cyclic citru-llinated peptide antibody. The concentration of FGF-23 was measured by ELISA (Immuntopics Inc., CA USA). Dual-energy x-ray absorptiometry was used to measure bone mineral density (BMD) of the lumbar spine (L1-L4) at the time of recruitment.
Results In comparison with control group, RA patients had elevated FGF-23 (p=0.041) and ESR (p<0.0001). In RA group, BMD (p=0.037), hemoglobin (p=0.004), and albumin (p<0.0001) were lower than control group. In both RA and Non-RA, ESR correlated negatively with BMD (r=-0.425, p=0.001), Hemoglobin (r=-0.473, p<0.0001), and albumin (r=-0.552, p<0.0001) and positively with FGF-23 (r=0.326, p=0.009). Also, Hemoglobin correlated negatively with FGF23 (r=-0.452, p<-0.0001) and positively with BMD(r=0.332, p=0.006). In only RA group, ESR correlated negatively with BMD (r=-0.43, p=0.005), hemoglobin (p=-0.426, p=0.005), and albumin (r=-0.489, p=0.001) but not correlated with FGF-23. However, Hemoglobin correlated negatively with FGF-23 (r=-0.442, p=0.003).
Conclusions In this study, Hemoglobin rather than inflammation is a negative predictor of plasma FGF-23 that is a potent regulator of the vitamin D and phosphate metabolism. Therefore, the association between ESR, anemia, FGF-23, and BMD loss in RA suggests a pathway between disease activity and BMD loss.
Disclosure of Interest None Declared