Laboratory Tests for PANDAS Diagnosis

Core Diagnostic Laboratory Tests

Antistreptolysin O (ASO) titer is typically obtained first to detect evidence of recent Group A Streptococcus (GAS) infection, as recommended by the American Heart Association, with a strength of evidence based on expert opinion 1, 2
Anti-deoxyribonuclease B (anti-DNase B) titer is particularly important if ASO is negative, as it may remain elevated longer than ASO, according to the American Heart Association guidelines 1, 2

ASO titers begin rising approximately 1 week after infection and peak 3-6 weeks later, providing a timeline for infection diagnosis 1
Anti-DNase B titers begin rising 1-2 weeks after infection and peak 6-8 weeks later, offering a window for detection 1
Both antibodies may remain elevated for several months after uncomplicated GAS infections, which can inform interpretation of test results 1

Normal levels of streptococcal antibodies are higher in school-age children than in adults, which can lead to misinterpretation, highlighting the need for age-specific reference ranges 1
Traditional neutralization assays for ASO and anti-DNase B are being replaced by newer latex agglutination or nephelometric assays, which may not be well standardized against traditional tests, requiring careful consideration of test methodology 1
A positive result requires careful interpretation in the context of clinical symptoms, as these antibodies reflect past rather than present immunologic events, emphasizing the importance of clinical correlation 1

Laboratory testing should be performed in the context of meeting clinical criteria for PANDAS, which include sudden onset of obsessive-compulsive symptoms and/or tics, as outlined by the American Academy of Pediatrics 3
A temporal relationship with GAS infection is a key criterion for PANDAS diagnosis, as stated by the Infectious Diseases Society of America 4

The American Heart Association does not recommend routine laboratory testing for GAS to diagnose PANDAS, as it is considered an "yet-unproven hypothesis", highlighting the need for further research 4

Post-treatment throat cultures are indicated only for patients who remain symptomatic or experience symptom recurrence, as recommended by the American Academy of Pediatrics 3