Anti-Sm Ab (RDL)

Anti-Sm Ab (RDL), often referred to as a connective tissue disease screen, supports the initial diagnostic assessment of suspected systemic autoimmune connective tissue diseases, including systemic lupus erythematosus, Sjögren syndrome, systemic sclerosis, polymyositis/dermatomyositis, and mixed connective tissue disease. The profile functions as an early triage tool to identify autoantibody-positive patients who should proceed to disease-specific antibody testing and comprehensive clinical evaluation.

Systemic connective tissue diseases represent a heterogeneous set of immune-mediated conditions that share overlapping mechanisms, clinical manifestations, characteristic laboratory patterns, and related therapeutic approaches. More than 200 disorders fall within this spectrum; frequently encountered examples include rheumatoid arthritis, polymyositis, dermatomyositis, systemic lupus erythematosus, systemic sclerosis, Sjögren syndrome, the systemic vasculitides, and mixed connective tissue disease. Because presentations are multisystem and variable, diagnosis is multidisciplinary and relies heavily on laboratory data. Autoantibody testing—such as ANA and antibodies to extractable nuclear antigens—supports case identification and differential diagnosis within this group of disorders.