{"id":"cd19-b-cells-percent","name":"CD19+ B Cells, percent","shortName":"B cells (%)","aliases":["CD19 %","CD19+ Percent","% CD19+","CD19 Cells %","B Cells %","CD19+ B Cells, Percent","% CD19+ Lymphs","B Cell Percent","Percent B Cells","B Lymphocytes %","CD19+ B Cells %"],"abbreviations":["% CD19"],"loinc":[{"code":"8117-4","primary":true},{"code":"20593-0","primary":false}],"specimen":"whole-blood","units":[{"ucum":"%","display":"% of lymphocytes"}],"referenceRanges":[{"population":"16+","low":3,"high":25,"unit":"%","unitDisplay":"% of lymphocytes","note":"Labcorp adult interval for CD19+ B cells as a percent of lymphocytes (test 505370, 95% confidence interval). ARUP Laboratories prints 6 to 23% for ages 16 to 64 (5 to 21% from age 65), so compare with the range on your own report. Labcorp's interval is kept because it is one of the two largest US labs and its result code is the primary LOINC code here. B cells are usually below 1% of lymphocytes in X-linked agammaglobulinemia (Salzer 2019).","sources":[{"title":"T- and B-Lymphocyte and Natural Killer Cell Profile (test 505370)","url":"https://www.labcorp.com/tests/505370/t-and-b-lymphocyte-and-natural-killer-cell-profile","publisher":"Labcorp"},{"title":"Lymphocyte Subset Panel 5 - Total Lymphocyte Enumeration (test 0095892)","url":"https://ltd.aruplab.com/Tests/Pub/0095892","publisher":"ARUP Laboratories"},{"title":"Flow Cytometry in the Diagnosis and Follow Up of Human Primary Immunodeficiencies","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC6893889/","publisher":"EJIFCC (International Federation of Clinical Chemistry and Laboratory Medicine)","year":2019}]}],"review":{"status":"ai-verified","label":"AI-verified against cited sources. Awaiting expert review","lastReviewed":"2026-10-03"},"summary":"The share of your lymphocytes that are B cells. B cells are the white blood cells that grow into antibody-making cells.","url":"https://bloodtesttracker.com/markers/cd19-b-cells-percent","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}