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Test ID CD20B CD20 on B Cells, Blood

Useful For

Evaluation of CD19 deficiency in patients with a suspected CD19 deficiency (humoral immunodeficiency)


Confirming complete absence of B cells in suspected primary humoral immunodeficiencies using both CD19 and CD20 markers


Assessing therapeutic B-cell depletion quantitatively (absolute counts of cells/mcL) in any clinical context, including malignancies, autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, and membranous glomerulonephritis among others, and treatment or prevention of acute humoral rejection in positive crossmatch renal transplant recipients


This test is not useful for assessing whether B cells express the target molecule (CD20) in the context of initiating therapeutic monoclonal anti-CD20 antibody therapy (rituximab, ofatumumab, and tositumomab) for any of the hematological malignancies, or in other clinical contexts, such as autoimmunity, instead order CEE20 / CD20 Cell Expression Evaluation, Varies.

Method Name

Flow Cytometry

Reporting Name

CD20, B-Cells

Specimen Type

Whole Blood EDTA

Ordering Guidance

This is the correct test to order if specifically confirming the absence of B cells due to suspected primary humoral or combined immunodeficiency or evaluating for CD19 deficiency.


If desirous of only quantitatively measuring total CD19 or CD20+ B cells, order TBBS / Quantitative Lymphocyte Subsets: T, B, and Natural Killer (NK) Cells, Blood or CD20B / CD20 on B Cells, Blood, respectively. Do not order the detailed analysis of B cell subsets for this purpose.


This test should not be ordered for a comprehensive evaluation of peripheral B-cell subsets. For evaluation of memory B-cell subsets, transitional B cells, mature and immature B cells, order IABCS / B-Cell Phenotyping Profile for Immunodeficiency and Immune Competence Assessment, Blood.


This test should not be used for evaluating presence of CD20 on malignant or nonmalignant B cells. The following test should be used instead, CEE20 / CD20 Cell Expression Evaluation, Varies.

Shipping Instructions

Collect and package specimens as close to shipping time as possible. It is recommended that specimens arrive within 24 hours of collection.

Necessary Information

Date of collection is required.

Specimen Required

For serial monitoring, we recommend that specimen collection be performed at the same time of day.


Container/Tube: Lavender top (EDTA)

Specimen Volume: 3 mL

Collection Instructions: Send specimen in original tube. Do not aliquot.

Additional Information:

1. Secondary aliquot tubes will be rejected.

2. Testing will be canceled if the specimen is not received ambient.

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood EDTA Ambient 4 days PURPLE OR PINK TOP/EDTA

Reference Values


≥19 years: 4.6-22.1%



≥19 years: 56.6-417.4 cells/mcL



≥19 years: 5.0-22.3%



≥19 years: 74.4-441.1 cells/mcL



18-55 years: 0.99-3.15 thou/mcL

>55 years: 1.00-3.33 thou/mcL

Day(s) Performed

Monday through Sunday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information



LOINC Code Information

Test ID Test Order Name Order LOINC Value
CD20B CD20, B-Cells In Process


Result ID Test Result Name Result LOINC Value
89584 CD45 Absolute 27071-0
29579 %CD19 B-Cells 8117-4
29580 %CD20 B-Cells 8119-0
29581 CD19 Absolute 8116-6
29582 CD20 Absolute 9558-8
29583 Comment 48767-8

Test Classification

This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

Report Available

Same day/1 to 2 days

NY State Approved