Red Blood Cell Morphology with Specific Focus on Red Blood Cell Distribution Width (RDW) and Red Blood Cell Count
This test measures two key components of your red blood cells: the **Red Blood Cell Distribution Width (RDW)**, which reflects the variation in size of your red blood cells, and the **red blood cell count**, which shows how many red blood cells are in your blood.
["Understanding your RBC size variation and count helps identify potential blood disorders or overall health status."]
Key facts at a glance
- LOINC
- 100432-4
- Short code
- LRBA-FC
- Synonyms
- Cells.LRBA+/B Cells NFr Bld FC
- Category
- chemistry
- Sample
- whole-blood
- Container
- EDTA anticoagulant tube (preferred for flow cytometry immunophenotyping). Sodium heparin tubes are also acceptable. ACD (acid citrate dextrose) tubes may be used as alternative.
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- flow-cytometry
- CPT
- 88184 (Flow cytometry, cell surface, cytoplasmic, or nuclear marker, technical component only; first marker) and 88185 (each additional marker), or 86355 (B-lymphocyte cell subset enumeration) depending on payer-specific bundling
- SNOMED
- 44294000 (Lymphocyte) | 261039000 (B-lymphocyte subset analysis) | 39579001 (Flow cytometry procedure)
- Specimen volume
- 3-5 mL of whole blood for adults; 1-3 mL for pediatric patients. Minimum 1 mL required for analysis.
- Stability
- Specimen should be processed within 24-48 hours of collection when stored at room temperature (18-25°C). If processing is delayed beyond 48 hours, store at 2-8°C. Do not freeze whole blood. Best results are obtained when specimen is processed within 24 hours of collection.
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 24–72 hours
- Order
- routine
Why RDW Matters: An Indicator of Red Blood Cell Health
RDW measures the spread in size of your red blood cells. Normally, red blood cells are similar in size, but if they vary widely, it may signal conditions like anemia (due to iron deficiency, vitamin deficiencies, or other causes), early stages of certain blood disorders, or even chronic diseases. High RDW can sometimes be a red flag for underlying health issues that need further investigation.
What Your RBC Count Tells You
Your red blood cell count tells doctors how many red blood cells are in your blood. While this test alone doesn’t diagnose anemia, it’s often checked alongside other blood tests. Low RBC counts may suggest blood loss, bone marrow problems, or other conditions affecting red blood cell production.
Common Causes of Abnormal RDW and RBC Counts
Changes in RDW and RBC counts can be influenced by many factors, including nutritional deficiencies (like iron or vitamin B12), chronic illnesses (such as kidney disease or liver problems), certain medications, or even stress. Some conditions, like sickle cell disease or thalassemia, also affect these values.
When You Might Need This Test
Your doctor may order this test if you have symptoms like fatigue, pale skin, shortness of breath, or unusual bruising. It’s also part of routine blood work to monitor overall health, especially if you have conditions like anemia or chronic diseases.
Reference range
Reference ranges for LRBA+ cells within CD19+ B-lymphocyte population are laboratory-specific and should be established by each performing facility. Generally reported as percentage of LRBA-positive cells among total CD19+ B-cells or as mean fluorescence intensity (MFI). Expected pattern: LRBA is constitutively expressed in most B-lymphocytes. Absence or marked reduction of LRBA expression in B-cells is suggestive of LRBA deficiency and should prompt confirmatory genetic testing.N/A
No fasting required. Recent corticosteroid or immunosuppressive therapy may affect lymphocyte populations and LRBA expression. Patients should be evaluated at baseline immunologic status when possible. Inform laboratory of any current immunomodulatory medications. Avoid scheduling during acute infection if possible, as transient lymphopenia may affect results.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
High RDW combined with low RBC count may indicate anemia or other blood disorders. Doctors use these results to tailor treatments, such as recommending supplements (like iron or folic acid) or further testing to identify the root cause. For example, if RDW is high but RBC count is normal, it might suggest a different type of blood problem that requires specialized evaluation.
Short name
RDW and RBC Count (Serum/Plasma)
Frequently asked questions
Why do I need this test if I feel fine?
What does a high RDW mean, and should I worry?
Can diet or lifestyle changes affect my RBC count or RDW?
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