Hematocrit
Also written as: Hct, Packed cell volume
The percentage of your blood volume made up of red blood cells.
What it measures
The proportion of your total blood volume that consists of red blood cells, expressed as a percentage.
Why a doctor orders it
It moves closely with hemoglobin and is used alongside it to assess for anemia or an overly concentrated blood volume.
What is generally associated with a higher result
Broadly associated with the same things that raise hemoglobin: dehydration, high altitude, smoking, chronic lung disease, and bone marrow disorders that overproduce red cells.
What is generally associated with a lower result
Broadly associated with anemia from any cause, blood loss, overhydration, and pregnancy.
Everyday things that move this number
Not every shift in a value reflects disease. These are ordinary factors known to affect this particular measurement:
- Hydration status
- Altitude
- Pregnancy
- Recent blood donation
Questions to take to your appointment
- Does this match my hemoglobin result?
- Could dehydration explain this reading?
Build a printable questionnaire with your own results →
Where to read more
MedlinePlus, from the US National Library of Medicine, publishes patient-facing pages on individual lab tests and is a reliable next stop: medlineplus.gov/lab-tests .
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