BTG3 and rheumatoid arthritis: When DED is secondary to a systemic condition, additional laboratory tests can help identifying the etiology of DED: Anti-Ro, anti-La, ANA (Sjögren syndrome); rheumatoid factor (rheumatoid arthritis); antithyroid peroxidase antibody and antithyroglobulin antibody (TED); and serum lysozyme and ACE (sarcoidosis) [38].