Other testing (eg, antineutrophil cytoplasmic antibodies [ANCA], rheumatoid factor, anticyclic citrullinated peptide [anti-CCP] antibody, antinuclear antibodies [ANA], C3 and C4 complement levels, cryoglobulin levels, nuclear antigens and antibodies to extractable nuclear antigens such as anti-Smith, anti-Ro / SSA, anti-La / SSB, and anti-RNP) may suggest other diagnoses, such as rheumatoid arthritis, systemic lupus erythematosus, or Sjögren syndrome.