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Red Blood Cell Count with Differential (Complete Blood Count - Differential)

Published: August 9, 2026Updated: August 17, 2026

This test measures the number of red blood cells and the proportions of different white blood cell types in your blood. It helps assess your overall health, detect infections, or identify blood disorders.

Quick summary

["A CBC with differential helps doctors diagnose and monitor conditions like anemia, infections, or blood cancers."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC
26454-9
Short code
RBC # CSF
Synonyms
RBC # CSF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Ref low
4.2
Ref high
5.9
Critical range
2 N/A – 7 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
85041
SNOMED
900000000000003001
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

What Does This Test Measure?

The test includes a count of red blood cells (RBCs) and evaluates five types of white blood cells (neutrophils, lymphocytes, monocytes, eosinophils, and basophils). These counts help identify whether your immune system or blood production might be affected.

Why Might I Need This Test?

Your doctor may order this test if you have symptoms like fatigue, frequent infections, unusual bruising, or unexplained weight loss. It’s also used during routine check-ups or to monitor chronic conditions like anemia or cancer.

How Is the Test Performed?

A small blood sample is taken from a vein, usually in your arm. The sample is then analyzed in a lab to count cells and identify their types. The process is quick and typically painless.

What Are Common Results?

Results show absolute counts for each cell type, which can vary based on age, health, and other factors. Abnormal counts may signal underlying health issues that need further investigation.

Reference range

Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A

Specimen: csf

No special preparation required. Stay well hydrated.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

CBC with Differential

Frequently asked questions

What Does a Low or High Red Blood Cell Count Mean?
A low red blood cell count (anemia) may suggest iron deficiency, chronic illness, or blood loss. A high count (polycythemia) could indicate dehydration, lung disease, or a blood disorder. Your doctor will discuss findings with you during your visit.
How Often Should I Get This Test?
Frequency depends on your health status. Routine adults may get a CBC every few years, while those with chronic conditions may need it more often. Follow your doctor’s recommendations.
Can I Prepare for This Test?
No special preparation is needed, but avoid heavy meals or strenuous activity 1–2 hours before the draw. Stay hydrated unless your doctor advises otherwise.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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 17, 2026. · Read our editorial policy