Understanding Strep Titers and PANDAS Flares
Strep titers are one of the most misunderstood lab values in a PANDAS workup. A normal titer does not mean no strep exposure. An elevated titer does not confirm PANDAS. Here is what they actually tell you.
ASO vs. Anti-DNase B
Antistreptolysin O (ASO) measures antibodies against a streptococcal toxin and is most commonly ordered. Anti-DNase B is more sensitive for certain strep strains and stays elevated longer. Most PANDAS evaluation protocols recommend ordering both — running only one misses the picture in approximately 20% of cases.
Why Titers Can Be Normal During a Flare
Titers are a lagging indicator. After strep infection, titers peak 4–6 weeks post-infection and decline over months. A child in an active flare may have a normalizing titer if the triggering infection occurred 3+ months ago. A normal result does not mean no recent exposure — it may mean the test was done too late.
The Exposure Log Is More Actionable
For day-to-day management, logging strep exposure is more clinically actionable than tracking titers. Log confirmed strep diagnoses in household members, rapid test results, school absences, and known exposures. This exposure log mapped against symptom data establishes the temporal relationship central to PANDAS diagnosis.
Serial Titers: When Repeat Testing Matters
A rising titer — even if both values are within "normal" range — confirms recent strep exposure. Two titer values taken 4–6 weeks apart tell a more complete story than any single result.
PANDAS Tracker lets you log strep exposures and titer values alongside daily symptom data. Free on iOS and Android.