From the Guidelines
Anti-double stranded DNA (anti-dsDNA) antibodies should be tested in all ANA-positive cases with clinical suspicion of Systemic Lupus Erythematosus (SLE), using a double-screening strategy with a last-generation SPA as the first step and CLIFT as the confirmation test, as recommended by an expert panel in 2023 1.
Importance of Anti-dsDNA Testing
Anti-dsDNA antibodies are autoantibodies primarily associated with SLE, targeting the body's own DNA and highly specific for SLE, with approximately 70-80% of SLE patients testing positive.
- Anti-dsDNA testing is valuable for both diagnosis and monitoring disease activity in lupus patients.
- Elevated levels often correlate with active disease, particularly lupus nephritis (kidney involvement).
- The test is typically ordered when a patient presents with symptoms suggestive of SLE, such as joint pain, skin rashes, fever, or kidney problems.
Interpretation of Test Results
- Normal values are generally below 30 IU/mL, though reference ranges may vary between laboratories.
- Rising anti-dsDNA levels may indicate an impending disease flare, allowing for preemptive treatment adjustments.
- These antibodies form immune complexes that deposit in tissues, particularly the kidneys, triggering inflammation and organ damage.
- While highly specific for SLE, anti-dsDNA should be interpreted alongside other clinical findings and laboratory tests, including ANA (antinuclear antibody), complement levels, and other lupus-specific antibodies for comprehensive evaluation, as suggested by recent studies 1.
Clinical Application
- The guidelines recommend testing the presence of anti-dsDNA in all ANA-positive cases with clinical suspicion of SLE.
- When ANA are negative, investigating the presence of anti-dsDNA is not recommended except when there is a high degree of clinical suspicion.
- The reference method for anti-dsDNA detection is considered the Farr assay, but it is not used in clinical practice due to its limitations, and instead, a double-screening strategy using a last-generation SPA and CLIFT is recommended 1.
From the Research
Ana and dsDNA
- The question about Ana and dsDNA appears to be related to the diagnosis of systemic lupus erythematosus (SLE) and the use of antinuclear antibodies (ANA) and anti-double stranded DNA (anti-dsDNA) as screening tools 2.
- According to a study published in 2013, ANA and anti-dsDNA have high sensitivity and specificity in patients with SLE, even when using sera from patients with multiple medical problems as controls 2.
- The study found that the prevalence of ANA at a titer of ≥1:80 and ≥1:160 was 8% and 4%, respectively, in healthy controls, and 12% and 6%, respectively, in patients with multiple medical problems 2.
- The prevalence of anti-dsDNA was 0% in healthy controls and 3% in patients with multiple medical problems 2.
- The sensitivity of ANA at a titer of ≥1:80 and ≥1:160 was 98% and 90%, respectively, with specificity of 92% and 96%, respectively, when using healthy control sera for the diagnosis of SLE 2.
- The specificity of anti-dsDNA was 100% and 97%, when using sera from healthy controls and patients with multiple medical problems, respectively 2.
Anaerobic Infections
- The provided studies do not directly address the question about Ana and dsDNA in the context of anaerobic infections.
- However, some studies discuss the treatment of anaerobic infections using metronidazole and other antibiotics 3, 4, 5, 6.
- A study published in 1979 found that metronidazole was not uniformly effective in the treatment of anaerobic pleuropulmonary infections 3.
- Another study published in 2001 discussed the anti-anaerobic activity of various antibacterial agents, including metronidazole, and noted that the resistance rate to metronidazole remains low 4.
- A study published in 2021 found that metronidazole was highly active against all isolates of Bacteroides fragilis, a common anaerobic bacterium, and remained the first-line antimicrobial for empirical therapy 6.