Blood count
Hematocrit
LOINC 4544-3 · %
What it is
Hematocrit is the percentage of your blood volume made up of red blood cells. It reflects how oxygen-carrying your blood is.
Why it matters
It is a core anemia and hydration marker, read together with hemoglobin and red-cell indices.
What high values can mean
A higher value can reflect dehydration or an overproduction of red cells; it can also rise at high altitude.
What low values can mean
A lower value often points to anemia from blood loss, nutrient deficiency or reduced red-cell production.
How to improve it
Treating the cause — iron or vitamin levels, hydration, or an underlying condition — is what normalises hematocrit.
Food & lifestyle
Iron-rich foods (red meat, beans, leafy greens) and adequate B12/folate support healthy red-cell levels; stay well hydrated.
Preparing for the test
Part of a complete blood count (CBC); fasting is not required.
When to talk to a doctor
Discuss a low or high hematocrit with a doctor, especially with fatigue, breathlessness or dizziness.
Related markers
Sources
- MedlinePlus (NIH)
- Testing.com (AACC)
Content reviewed on June 26, 2026
Medical disclaimer
This content is for educational purposes only. It is not medical advice and does not diagnose, treat, or prevent any condition. Reference ranges vary between laboratories — always use the range printed on your report and discuss your results with a healthcare professional.
See your own values in context
Bllod turns your lab report PDFs into clear, tracked results — every marker organized, explained, and charted over time.