Most Commonly Associated Disease
Systemic lupus erythematosus (SLE)

Category
Antibody

When to Order
* High suspicion of rheumatic or connective tissue disease
* Consider if patient has high pre-test probability with presence of 2 or more of the following: lupus-associated rash, inflammatory arthritis, cytopenia, sicca (dry eyes and/or dry mouth in mornings)
* Order for KNOWN JIA – helps with disease prognosis

What It Means If Positive
* NOT SPECIFIC! 20% of healthy individuals will be positive, especially in low titer.
* Cross reacts with the following (so consider the following on differential diagnoses for positive ANA): autoimmune thyroid disease, liver disease, cancer, serositis, hematuria, proteinuria, Raynaud’s
* In JIA, +ANA=higher risk of anterior uveitis so more frequent ophtho screening needed!

What It Means If Negative
* VERY SENSITIVE! If negative, extremely unlikely patient has systemic lupus erythematosus
* Extremely low likelihood of systemic sclerosis or mixed connective tissue disease also

Of Note
* Reported as a titer. Considered LOW positive at 1:80. Extremely unlikely diagnosis of SLE if ANA ≦ 1:40.
* Clinically significant >= 1:160. HIGH positive (1:1280) more likely associated with pathology/disease development
* DOES NOT TREND WITH DISEASE ACTIVITY so no need to keep remeasuring