Lab Tests Reference Library

ANA is a screening test for autoimmune diseases. A positive ANA indicates the immune system is producing antibodies against the body's own cells. Found in Lupus (SLE), Sjögren's, and other autoimmune conditions.

Anti-dsDNA antibodies are highly specific for Systemic Lupus Erythematosus (SLE/Lupus). Rising levels often correlate with lupus flares and kidney involvement.

Rheumatoid Factor is an antibody found in rheumatoid arthritis and other autoimmune conditions. A positive RF combined with joint symptoms supports the diagnosis of RA.

Anti-CCP (anti-cyclic citrullinated peptide) antibodies are highly specific for Rheumatoid Arthritis. More specific than RF and can be positive years before symptoms appear.

C3 is the most abundant complement protein. Low C3 suggests complement consumption in active autoimmune disease (especially lupus nephritis) or genetic C3 deficiency.

C4 is a complement protein involved in immune complex clearance. Low C4 with low C3 strongly suggests active lupus. C4 can also be low in hereditary angioedema.

IgG is the most abundant immunoglobulin, providing long-term immunity. Low IgG indicates immune deficiency; high IgG may suggest chronic infection, autoimmune disease, or multiple myeloma.

Total IgE is elevated in allergic conditions (asthma, atopic dermatitis, hay fever) and parasitic infections. Very high IgE can also suggest hyperIgE syndrome.