The Anti-dsDNA Antibody – Titre test measures the concentration (titre) of antibodies against double-stranded DNA (dsDNA) in the blood. This test is crucial in diagnosing and monitoring systemic lupus erythematosus (SLE), as elevated levels of these antibodies are often associated with the disease. The titre indicates the quantity of antibodies present, and higher titres may suggest more active or severe disease. A blood sample is required for this test, which helps in assessing disease activity and guiding treatment decisions for lupus patients.