From the Guidelines
Repeating the ANA test is not necessary for a patient with a previously elevated ANA of 1:160 who now has a negative rheumatoid factor without a recent ANA, unless new or worsening symptoms develop that suggest an autoimmune condition. According to the European League Against Rheumatism recommendations for monitoring patients with systemic lupus erythematosus, the monitoring of autoantibodies and complement, including ANA, is recommended at baseline, but re-evaluation in previously negative patients is only recommended in specific situations, such as prior to pregnancy, surgery, transplant, or use of estrogen-containing treatments, or in the presence of a new neurological or vascular event 1. ANA levels can fluctuate over time and may even become negative in patients with autoimmune conditions. A low-titer positive ANA of 1:160 is relatively common and can be found in approximately 20% of healthy individuals, particularly older adults and women. The clinical significance of ANA should always be interpreted in the context of the patient's symptoms, physical examination findings, and other laboratory results. If the patient is not currently exhibiting symptoms suggestive of an autoimmune disease, watchful waiting with regular clinical follow-up is reasonable. Key points to consider include:
- The patient's previous ANA result and current negative rheumatoid factor
- The absence of symptoms suggestive of an autoimmune disease
- The potential for ANA levels to fluctuate over time
- The need for regular clinical follow-up to monitor for new or worsening symptoms.
From the Research
Repeating ANA Tests
- The decision to repeat an ANA test for a patient with a previously elevated ANA of 1:160 who recently tested negative without an ANA, and has a negative rheumatoid factor, depends on various factors, including the clinical context and the methodology used for the test 2.
- According to a study published in 2013, the ANA test can be a useful laboratory tool to help confirm or exclude the diagnosis of systemic rheumatic disease, but its results can be difficult to interpret due to the relatively high prevalence of ANAs in other inflammatory conditions and healthy individuals 3.
- Another study published in 2021 suggests that ANA prevalence in healthy persons has increased over the last decades, and that considering ANA titers ≤1:320 as a serological marker of autoimmune diseases may be inappropriate 4.
- The classification and diagnosis of systemic autoimmune diseases often rely on a collection of criteria, including clinical, laboratory, imaging, and pathology elements, with autoantibodies playing a prominent role 5.
- In clinical practice, repeating a test like ANA may be important to eliminate the possibility of a rare type of error, especially for tests that are critical for clinical decision-making 6.
Considerations for Repeating the Test
- The patient's clinical presentation and medical history should be taken into account when deciding whether to repeat the ANA test 2.
- The methodology used for the ANA test, such as indirect immunofluorescence or multiplex bead assay, can affect the results and should be considered when interpreting the test 2.
- The predictive value of a positive ANA test is low if the test is performed in the absence of a reasonable likelihood of autoimmune disease, highlighting the importance of careful test selection and interpretation 2.