RETN and rheumatoid arthritis: Overall, the complex picture of several adipokines and their isoforms with different and even opposing effects could explain the fact that we did not observe a relationship between serum levels of the other adipokines examined (adiponectin, leptin, chemerin, resistin, and omentin) and subsequent development of arthritis.Adipokine levels are elevated in the synovial compartment of established RA patients, which suggests local production in the inflamed joint.