{"id":"il-6","name":"Interleukin-6 (IL-6)","shortName":"IL-6","aliases":["Interleukin 6","Interleukin-6","Interleukin-6, Serum","Interleukin-6, Plasma","IL-6","IL6","IL-6, Serum","IL-6, Plasma","IL-6 Level"],"abbreviations":["IL-6","IL6"],"loinc":[{"code":"26881-3","primary":true}],"specimen":"serum-or-plasma","units":[{"ucum":"pg/mL","display":"pg/mL"},{"ucum":"ng/L","display":"ng/L"}],"referenceRanges":[{"population":"Adults","low":0,"high":6.4,"unit":"pg/mL","unitDisplay":"pg/mL","note":"Mayo Clinic Laboratories prints '<6.4 pg/mL' for adult serum (treated as inclusive here). This is one lab's own limit. IL-6 assays are not standardized, and published limits range widely: a Japanese hospital study quoted a normal range of under 8.0 pg/mL, and a 2026 study of healthy adults in China using a different method found an upper limit of 2.23 pg/mL. Many healthy people read near the lowest amount the test can detect. Use the range on your own report.","sources":[{"title":"Interleukin-6, Serum (Mayo test ID IL6DX)","url":"https://schnecklab.testcatalog.org/show/IL6DX","publisher":"Mayo Clinic Laboratories (catalog page mirrored on testcatalog.org)"},{"title":"Interleukin-6 levels decrease following rituximab treatment but increase following tocilizumab treatment","url":"https://doi.org/10.1007/s00277-026-07130-w","publisher":"Annals of Hematology","year":2026},{"title":"Establishment of reference intervals for plasma IL-6, IL-8, IL-10, and IL-1β in healthy adults from Lianyungang, Jiangsu, China: a single-center flow cytometry analysis","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC13212108/","publisher":"Frontiers in Medicine","year":2026}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"A signaling protein your immune system releases early in infection and inflammation. It is ordered in specific situations, not at routine check-ups.","url":"https://bloodtesttracker.com/markers/il-6","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}