{"id":"aso","name":"Antistreptolysin O (ASO) titer","shortName":"ASO","aliases":["Anti-Streptolysin O","ASO Titer","Antistreptolysin O","ASO, Quantitative","ASO","ASLO","Antiestreptolisinas O","Antiestreptolisina O","Antistreptolysin O Antibody","Anti-Streptolysin O Antibody (ASO)","Antistreptolysin O (ASO) Antibodies","ASO Antibodies","Streptolysin O Antibody","ASOT","ASO Titre","Antistreptolysin Titre"],"abbreviations":["ASO","ASOT","ASLO"],"loinc":[{"code":"5370-2","primary":true},{"code":"25788-1","primary":false},{"code":"22568-0","primary":false},{"code":"5371-0","primary":false},{"code":"9788-1","primary":false}],"specimen":"serum","units":[{"ucum":"[IU]/mL","display":"IU/mL"}],"referenceRanges":[{"population":"18+","low":0,"high":200,"unit":"[IU]/mL","unitDisplay":"IU/mL","note":"Labcorp's interval for its latex immunoturbidimetry assay, 0.0-200.0 IU/mL, with no age split shown on its test page. ASO upper limits are conventionally set at the 80th percentile of a local population, not the central 95%, so they differ by lab, assay, age and region. An independent study of 267 healthy adults aged 30-70 in Aleppo, Syria (turbidimetry) found an 80th-percentile upper limit of 210.8 IU/mL (256 at ages 30-39, falling to 158 at ages 60-70), which is in the same range. Children's upper limits are higher and depend on age and method, so this range is for adults only. Other labs and assays use their own cut-offs, so use the range printed on your report.","sources":[{"title":"Antistreptolysin O (ASO) Antibodies (test 006031)","url":"https://www.labcorp.com/tests/006031/antistreptolysin-o-aso-antibodies","publisher":"Labcorp","year":2023},{"title":"Normal values of antistreptolysin O for adults ages 30 to 70 in Syria: A cross sectional study","url":"https://doi.org/10.1016/j.amsu.2021.103015","publisher":"Annals of Medicine and Surgery","year":2021}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"Measures antibodies your body makes against a toxin from group A strep bacteria, which can show a strep infection in the recent past.","url":"https://bloodtesttracker.com/markers/aso","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}