Objective: To explore the associated diseases with positive anti-double stranded (ds) DNA other than systemic lupus erythematosus (SLE), and to determine an association if any, between its level in non-SLE causes.
Methods: This is a retrospective review of all patients with positive anti-dsDNA assay (more than 200 IU/ml) tested for any underlying etiology from January to December 2007 at King Abdul-Aziz University Hospital, Jeddah, Kingdom of Saudi Arabia.
Results: Two hundred and twelve patients with anti-dsDNA antibody testing were evaluated. Of these, 124 patients had SLE (58.5%), while 88 patients (41.5%) had other diseases. Representing non-SLE diseases were: rheumatological disorders in 29 patients (33%), infections in 11 (12%), and malignancy in 6 patients (7%). Strong positive results (>800 IU/ml) were found in only 8 patients (4%) with diagnoses of antiphospholipid antibody syndrome, tuberculosis, osteomylitis, thymoma, lymphoma, sarcoidosis, and 2 autoimmune hepatitis patients. There was a statistically significant association between highly positive anti-dsDNA testing and rheumatological disorders.
Conclusion: Although positive anti-dsDNA test is common in SLE patients, other diseases should be considered when the anti-dsDNA level is equivocal, and the clinical criteria are not in favor of SLE.