Red Blood Cell Count (with Differential Analysis)
This test measures the number of red blood cells in your blood and evaluates the proportions of different white blood cell types.
["Assesses overall blood health and immune system balance."]
Key facts at a glance
- LOINC
- 20476-8
- Short code
- CD1A
- Synonyms
- CD1a Cells NFr Bld
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA (lavender-top) blood collection tube, sterile
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Flow cytometry immunophenotyping using fluorescently labeled monoclonal antibodies against CD1a surface marker
- CPT
- 86355
- SNOMED
- 395124008
- Specimen volume
- 3-5 mL whole blood; minimum 1 mL for pediatric samples
- Stability
- Specimen should be processed within 24-48 hours of collection when stored at room temperature (18-25°C). Do not refrigerate or freeze. Stability may vary by laboratory protocol.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
What This Test Measures
The test includes a **red blood cell (RBC) count**, which determines the total number of RBCs in your blood. It also provides a **white blood cell differential**, breaking down the types of white blood cells (neutrophils, lymphocytes, monocytes, eosinophils, basophils) to help identify immune or inflammatory activity.
Why It’s Done
Doctors may order this test to diagnose or monitor conditions like anemia, infections, blood disorders, or immune system issues. It helps assess how well your body is producing healthy blood cells and whether there are imbalances in your immune response.
Sample Collection and Preparation
A small blood sample is drawn from a vein, usually in your arm. The blood is sent to a lab where it is analyzed to count RBCs and examine white blood cell types. No special preparation is needed, but fasting may be advised for some related tests.
Common Conditions Monitored
Abnormal results may signal conditions such as infections (e.g., high neutrophils), chronic inflammation, blood cancers (e.g., low RBCs or skewed differentials), or autoimmune disorders. Low RBC counts could indicate anemia, while high counts might suggest dehydration or polycythemia.
Reference range
CD1a-positive cells are typically reported as percentage of total lymphocytes or as absolute count. Reference ranges vary by laboratory; generally CD1a expression on peripheral blood lymphocytes is minimal in healthy adults (<1% of lymphocytes).N/A
No special patient preparation required. Recent immunotherapy, corticosteroid use, or chemotherapy may affect results and should be documented.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
RBC Count with Differential
Frequently asked questions
How long will it take to get my results?
Can I eat or drink before this test?
What does a ‘normal’ differential look like?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy