Which disease is characterized by positive ANA and anti-Sm labs?

The disease characterized by positive antinuclear antibodies (ANA) and anti-Smith (anti-Sm) antibodies is systemic lupus erythematosus (SLE), commonly referred to as lupus.

In lupus, the presence of ANA is a hallmark, as these antibodies are found in a diverse range of autoimmune conditions, but they are particularly prevalent in lupus. The specificity of anti-Sm antibodies is notable, as they are considered a classic marker for SLE and are not typically found in other autoimmune diseases. The significance of these antibodies lies in their connection to the disease's pathophysiology, particularly in the context of the varied clinical manifestations of lupus.

In distinguishing lupus from other conditions such as rheumatoid arthritis, multiple sclerosis, or scleroderma: rheumatoid arthritis primarily presents with different autoantibodies, such as rheumatoid factor and anti-CCP, while multiple sclerosis is not associated with ANA or anti-Sm. Scleroderma may also show a positive ANA but is more closely linked to other specific autoantibodies, such as anti-Scl-70 or anti-centromere.

Thus, when both positive ANA and anti-Sm are detected, the strong association with lupus confirms it as the correct diagnosis.