Red Blood Cell (RBC) Mass Concentration in Whole Blood
This test measures the total amount of red blood cells in your blood, expressed as a mass concentration. It helps assess your blood’s cellular composition and overall health.
["Understanding your RBC levels can help identify anemia or other blood-related conditions."]
Key facts at a glance
- LOINC
- 40431-9
- Short code
- OF Fresh RBC Cont-Imp
- Synonyms
- OF Fresh RBC Cont-Imp
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- 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
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What Is This Test Measuring?
This test quantifies the mass concentration of red blood cells (RBCs) in your blood sample. RBCs are the cells responsible for carrying oxygen throughout your body. The result is typically reported in units of mass per volume (e.g., grams per liter), though exact units may vary by lab.
Why Might You Need This Test?
Doctors may order this test to evaluate symptoms like fatigue, pale skin, shortness of breath, or unusual tiredness. It can also be part of routine blood work to monitor chronic conditions such as anemia, kidney disease, or other blood disorders.
How Is This Test Performed?
A small blood sample is drawn from a vein, usually in your arm. The sample is then analyzed in a lab to determine the RBC mass concentration. This test is typically performed on whole blood.
What Are Common Reasons for Abnormal Results?
Low RBC mass (hypochromia or microcytosis) may indicate conditions like iron deficiency, vitamin deficiencies (e.g., B12 or folate), or chronic diseases. High RBC mass could suggest conditions like polycythemia or dehydration.
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.
This test is primarily used to support the diagnosis and management of blood-related disorders. It complements other blood tests, such as hemoglobin and hematocrit, to provide a fuller picture of your blood health. Results may be compared to reference ranges specific to your age, sex, and overall health.
Short name
RBC Mass
Frequently asked questions
What does a low RBC mass mean?
What does a high RBC mass mean?
How often should I get 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