The most common condition associated with a positive ANA test is systemic lupus erythematosus (SLE). About 95% of those with SLE have a positive ANA test result. Other conditions in which a positive ANA test result may occur include:
- Drug-induced lupus: A number of medications may trigger this condition, which is associated with SLE symptoms. Cessation of the drug typically stops the symptoms, which usually go away. Although many medications have been reported to cause drug-induced lupus, those most closely associated with this syndrome include hydralazine, isoniazid, procainamide, and several anticonvulsants.
- Sjögren syndrome: About 40-70% of those with this condition have a positive ANA test result. While this finding supports the diagnosis, a negative result does not rule it out. About 90% or more of individuals with Sjögren syndrome have autoantibodies to SSA.
- Scleroderma (systemic sclerosis): About 60-90% of those with scleroderma have a positive ANA. In people who may have this condition, ANA subset tests can help distinguish certain forms of the disease.
- Other less common conditions: Less commonly, ANAs may occur in people with Raynaud syndrome, arthritis, dermatomyositis or polymyositis, mixed connective tissue disease, and other autoimmune conditions.
Most clinicians must rely on test results, clinical symptoms, and patient history for the diagnosis. Since symptoms may appear and disappear, it may take months or years to show an ANA pattern that might suggest SLE or any of the other autoimmune diseases. A negative ANA result makes SLE an unlikely diagnosis. It usually is not necessary to immediately repeat a negative ANA test; however, due to the episodic nature of autoimmune diseases, it may be worthwhile to repeat the ANA test at a future date if symptoms recur.