Red Blood Cell Count with Autohematocrit
This test measures the number of red blood cells in your blood and calculates the percentage of blood volume that is made up of these cells, often done as part of a complete blood count (CBC).
["RBC count helps check for anemia or other blood disorders."]
Key facts at a glance
- LOINC
- 791-4
- Short code
- RBC # CSF Auto
- Synonyms
- RBC # CSF Auto
- 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
- automated-count
- CPT
- 85041
- SNOMED
- 900000000000003001
- Specimen volume
- 1-2 mL
- Stability
- Immediate analysis required, Refrigerated: 1h
- Hemolysis max
- 200
- TAT
- 4–24 hours
- Order
- routine
Why This Test Matters
Red blood cells (RBCs) carry oxygen from your lungs to the rest of your body. If your RBC count is too low, you may feel tired or weak. If it’s too high, you might have extra blood viscosity, which can strain your heart and lungs. This test helps doctors diagnose and monitor conditions like anemia, polycythemia, or bleeding disorders.
What to Expect During the Test
A small needle is used to draw a few drops of blood from your arm. The blood is then analyzed in a machine that automatically counts RBCs and calculates hematocrit (the percentage of blood volume made up of RBCs). This process usually takes a few minutes and is painless after the needle is removed.
Common Reasons for This Test
Doctors may order this test if you have symptoms like fatigue, pale skin, shortness of breath, or unusual bleeding. It’s also part of routine check-ups, before surgeries, or to monitor chronic conditions like kidney disease or anemia.
What the Results Mean
Your results will show your RBC count and hematocrit percentage. While exact reference ranges vary by lab, low values may indicate anemia, while high values could suggest conditions like dehydration, polycythemia, or lung disease. Always discuss your results with your healthcare provider.
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.
◆Associated findings1
Short name
RBC Count + Auto-Hematocrit
Frequently asked questions
How long does it take to get my RBC count and hematocrit results?
Can I eat or drink anything before this test?
Is there any risk or discomfort with this test?
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