{"id":"cd19-b-cells-absolute","name":"CD19+ B Cells, absolute","shortName":"B cells (absolute)","aliases":["Absolute CD19","CD19 Absolute","CD19 Abs Cnt","CD19+ Cells, Absolute","B Cells, Absolute","CD19+ B Cells Absolute","Abs.CD19+ Lymphs","B Cell Count","B Lymphocytes, Absolute","Absolute B Cells","CD19+ B Lymphocytes, Absolute"],"abbreviations":["Abs CD19"],"loinc":[{"code":"8116-6","primary":true},{"code":"15195-1","primary":false}],"specimen":"whole-blood","units":[{"ucum":"/uL","display":"cells/µL"},{"ucum":"10*3/uL","display":"×10³/µL"},{"ucum":"10*9/L","display":"×10⁹/L"},{"ucum":"10*6/L","display":"×10⁶/L"}],"referenceRanges":[{"population":"16+","low":12,"high":645,"unit":"/uL","unitDisplay":"cells/µL","note":"Labcorp adult interval for CD19+ B cells (test 505370, 95% confidence interval). Its lower limit is much lower than ARUP Laboratories' 91 to 610 cells/µL for ages 16 to 64 (74 to 510 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 undetectable (under 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":"How many B cells are in a microliter of blood. B cells are the white blood cells that grow into antibody-making cells.","url":"https://bloodtesttracker.com/markers/cd19-b-cells-absolute","notice":"Information, not medical advice. Ranges differ between labs, so the range on your own report is the one your result is judged against."}