The IdentRA is an ELISA test that detects the presence and amount of the 14-3-3η (eta) protein in the serum. This protein is one of seven isoforms of the 14-3-3 protein family, which are ubiquitous intracellular chaperones that regulate communication pathways involved in inflammation. Patients with RA and erosive psoriatic arthritis have high levels of this protein in the synovial fluid. The protein is thought to be secreted by synovial fibroblasts and synovial macrophages. Recent studies have demonstrated an association between elevated serum levels and subsequent evolution from undifferentiated arthritis to RA and/or erosive arthritis. Of note, elevated serum levels can be seen in a small percentage of healthy patients (15%), while established RA patients under good control can have normal values.