Plasma and synovial fluid lanthanides in rheumatoid arthritis: variations after intra-articular therapy

Lanthanides (Lnj, or rare earth elements, are detectable in trace amounts in organisms. Increased concentrations of Ln have been observed in rheumatoid arthritis (RA) in plasma (pi) and synovial fluid (Sf). We have evaluated pi and Sf concentrations of Ln (in particular La, Nd, Ce, Yb, Lu, Eu), in rheumatoid arthritis patients, before and after intra-articular steroid injection. Increased pi and Sf concentrations of Ln were confirmed in RA. No detectable synovial fluid concentrations of Ln were observed in healthy controls. A statistically significant Ln reduction (p < 0.001) was observed in Sf 3 and 6 days after local steroid injection and in pi after 6 days. The decrease in Ln concentrations in Sf and pi, after antiphlogistic therapy, reflects the reduction of the inflammatory condition.