Serum or plasma mass concentration of red blood cell volume (hematocrit)
This test measures the proportion of red blood cells in your blood, helping assess red blood cell health and overall blood volume.
["Hematocrit reflects red blood cell density and can signal anemia or polycythemia."]
Key facts at a glance
- LOINC
- 51641-9
- Short code
- MSCV RBC
- Synonyms
- MSCV RBC
- Category
- chemistry
- Sample
- whole-blood
- Container
- Lavender-top (EDTA)
- 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
- 3 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h
- Hemolysis max
- 0
- Lipemia max
- 0
- Icterus max
- 0
- TAT
- 4–24 hours
- Order
- routine
What Is Hematocrit Used For?
Hematocrit is commonly used to diagnose or monitor conditions like anemia (low red blood cells), polycythemia (high red blood cells), or dehydration. It also helps evaluate blood loss, kidney function, and certain blood disorders.
How Is It Collected?
A small blood sample is drawn from a vein, usually in your arm. The blood is then separated to measure the volume of red blood cells relative to the total blood volume.
When Might You Need This Test?
Your healthcare provider may order a hematocrit test if you have symptoms like fatigue, pale skin, shortness of breath, or if you’re being evaluated for conditions like anemia, kidney disease, or blood disorders.
What Are Common Results?
Results are typically reported as a percentage (e.g., 35%–52% for men, 38%–46% for women). While reference ranges vary by lab, lower values may indicate anemia, and higher values may suggest dehydration or other conditions.
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.
Hematocrit is a key indicator of red blood cell health and overall blood health. Low levels often signal anemia, which can cause fatigue or weakness, while high levels may indicate conditions like dehydration, polycythemia, or certain cancers. Regular monitoring can help manage chronic conditions like kidney disease or heart failure.
Short name
Hematocrit (Hct)
Frequently asked questions
Why might my hematocrit be checked during pregnancy?
What could cause my hematocrit to be abnormally low?
How often should I get a hematocrit 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