What are these tests for - ANA/dsDNA?
Q: In layman’s language please tell the purpose of the following blood tests – ANA/dsDNA. My MRI reveals multiple sclerosis suggestive of demyelination in my cervical cord region. My eyes and hearing are normal. My right side feels numb and the motor movements are intact apart from my right hand fourth and little finger. These have 30% impairment. What do I do?
A:Serologic (blood) tests for autoantibodies (antibodies formed against our own tissue), including tests for antinuclear antibodies (ANAs) and antibodies to specific nuclear antigens such as double-stranded DNA (dsDNA), play an important role in the diagnosis of systemic rheumatic diseases. Few tests yield results that are pathognomonic for particular diseases. For these reasons, test results for autoantibodies alone are insufficient to establish the diagnosis of a systemic rheumatic disease; they must always be interpreted in the clinical context. Positive results for tests such as the ANA test are seen quite commonly in patients with non-rheumatic diseases and even among normal, healthy persons. Antibodies binding to DNA belong to the group of anti-nuclear antibodies (ANA) that have been observed in several autoimmune diseases. Antibodies reacting with native double-stranded (ds) DNA are regarded as being specific for systemic lupus erythematosus (SLE) and have been observed in approximately 50-80% of the patients. Fluctuations in anti-dsDNA antibody levels are also used as markers for disease activity and exacerbation. ANA positivity is seen in diseases like SLE, systemic sclerosis, Sjogren’s syndrome, dermatomyositis or polymyositis, mixed connective tissue disease, etc. It is also used to monitor diseases like juvenile rheumatoid arthritis and Raynaud's phenomenon.