Red Blood Cell Count with Differential (Microhematocrit or Manual Differential)
This test measures your red blood cells (RBCs) and breaks down their types to help diagnose blood-related conditions.
["Understanding your blood cell composition can reveal issues like anemia, infections, or blood disorders."]
Key facts at a glance
- LOINC
- 18289-9
- Short code
- RBC CSF Micro
- Synonyms
- RBC CSF Micro
- 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
- Method
- microscopy-light
- 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 This Test Measures
The test includes a **red blood cell count** (total RBCs) and a **differential count**, which lists the proportions of different white blood cell types (neutrophils, lymphocytes, monocytes, eosinophils, basophils). Some labs may also report platelet counts or hematocrit as part of this panel.
Why It’s Done
Doctors order this test to check for blood disorders, infections, or other conditions affecting your immune system or blood cells, such as leukemia, anemia, or autoimmune diseases.
Sample Collection and Preparation
A small blood sample is drawn from a vein, typically in your arm. The sample is then examined under a microscope to count RBCs and classify white blood cells. Some labs may use a microhematocrit tube for hematocrit or RBC density measurements.
Common Reasons for Testing
This test is often performed if you have symptoms like fatigue, frequent infections, unexplained bruising, or unusual bleeding. It may also be part of routine check-ups or before certain treatments.
Reference range
Adult males: 4.2-5.9; Females: 3.8-5.1 x 10^12/LN/A
No special preparation required. Stay well hydrated.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Abnormal RBC counts or differentials can signal conditions like anemia (low RBCs), infections (elevated white cells), or clotting disorders (elevated platelets). For example, a high neutrophil count may indicate infection, while a low lymphocyte count could suggest immune suppression.
Short name
RBC Count + Differential
Frequently asked questions
What does a ‘microhematocrit’ or ‘manual differential’ mean?
Will I need to prepare for this test?
Can this test detect all blood disorders?
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 17, 2026. · Read our editorial policy