Anti-DNase B Antibody Testing
Anti-DNase B (anti-deoxyribonuclease B) antibody testing is used to confirm recent or past Group A Streptococcal (GAS) infection, particularly when evaluating suspected post-streptococcal complications such as acute rheumatic fever or acute glomerulonephritis. 1
Primary Clinical Indications
The anti-DNase B test serves as a critical confirmatory tool for diagnosing post-streptococcal sequelae, not for diagnosing acute pharyngitis. 1
Key Uses:
- Confirmation of recent GAS infection in patients with suspected acute rheumatic fever or acute glomerulonephritis 1, 2
- Secondary testing when ASO is negative or equivocal, as anti-DNase B may remain elevated when ASO titers have normalized 1, 2
- Particularly valuable in streptococcal skin infections (impetigo, pyoderma), where ASO titers are frequently not elevated but anti-DNase B titers are 3
Timing and Interpretation
Antibody Kinetics:
- Anti-DNase B titers begin rising 1-2 weeks after GAS infection and peak at 6-8 weeks post-infection 1, 2
- Elevated titers may persist for several months after even uncomplicated infections 1, 2
- This longer elevation period compared to ASO (which peaks at 3-6 weeks) makes anti-DNase B useful for detecting more remote infections 1, 2
Age-Specific Normal Values:
Critical pitfall: Normal anti-DNase B levels are significantly higher in school-age children than adults, and misinterpretation is common. 1, 2
- Preschool age: Upper limit of normal (ULN) approximately 1:60 3
- School age (2-12 years): ULN ranges from 240-480 units, with higher values in older children 3, 4, 5
- Adults: ULN approximately 160-340 units 3, 5
Clinical Algorithm for Use
When to Order Anti-DNase B:
- First-line test is ASO for suspected post-streptococcal complications 1, 2
- Order anti-DNase B if ASO is not elevated but clinical suspicion for post-streptococcal disease remains high 1, 2
- Consider ordering both tests simultaneously in cases of suspected acute rheumatic fever or acute glomerulonephritis to maximize diagnostic yield 3, 5
Diagnostic Performance:
- In acute rheumatic fever: Anti-DNase B is elevated in approximately 87% of cases 3
- In inactive rheumatic fever: Anti-DNase B shows 72% positivity versus only 22% for ASO 3
- Combined ASO and anti-DNase B testing detects streptococcal infection in up to 98% of proven cases 6
Important Caveats
What Anti-DNase B Does NOT Do:
- Cannot distinguish active infection from carrier state - reflects past immunologic events only 1
- Not recommended for routine diagnosis of acute pharyngitis - throat culture or rapid antigen testing is appropriate for acute diagnosis 1
- Serial testing is required for optimal interpretation, making it impractical for routine sore throat evaluation 1
Technical Considerations:
- Newer latex agglutination and nephelometric assays may not be well-standardized against traditional neutralization assays, requiring awareness of methodology used 1, 2
- Results must be interpreted with age-appropriate reference ranges to avoid false-positive interpretations 1, 2, 4
Practical Application
When evaluating a child with suspected acute rheumatic fever presenting 4-8 weeks after a possible streptococcal infection, order both ASO and anti-DNase B titers together to maximize the likelihood of documenting recent GAS infection, as one or both will be elevated in the vast majority of cases. 1, 3 This combined approach is particularly important because anti-DNase B may be the only elevated marker in cases of streptococcal skin infection or when sufficient time has elapsed for ASO to normalize. 3, 5