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Haematology
PCV, or packed cell volume, tells your doctor what share of your blood is made up of red blood cells. A lab spins your blood sample in a centrifuge until the red cells settle into a compact layer at the bottom of the tube, separated from the plasma above, and measures how much of the total column that red cell layer takes up. The result is a single percentage. It's ordered on its own when a doctor wants a quick, focused check on red cell mass, for example to track dehydration, monitor a known case of anaemia or polycythemia, or recheck a value without repeating a full blood count.
The report gives one number: the percentage of your blood volume occupied by red blood cells. A low percentage generally points toward anaemia or blood loss, while a high percentage can reflect dehydration, a bone marrow condition that overproduces red cells, or reduced oxygen levels from lung or heart conditions. Because PCV moves in the same direction as haemoglobin and red cell count, doctors often view it alongside those values rather than in isolation, even when it's ordered as a standalone test.
Red blood cells make up a large share of blood volume, and packed cell volume is simply the percentage of that volume they occupy once separated from plasma by centrifugation. It's one of the oldest and simplest measurements in laboratory haematology, and it remains useful precisely because it's fast and doesn't need complex instrumentation.
Anything that changes how many red cells you have, or how much plasma is diluting them, shifts this number. Blood loss, red cell destruction, or a bone marrow that isn't producing enough red cells lowers it. Dehydration concentrates the blood and raises it without any real change in red cell mass, while conditions like polycythemia vera raise it through genuine overproduction of red cells.
A full complete blood count gives PCV along with several other values, but a doctor may want just this one number, for instance to see whether IV fluids have corrected dehydration, to follow a stable anaemia over time without repeating a longer panel, or to monitor someone with a known red cell disorder between fuller check-ups. Expected values differ between men and women because of differences in average red cell mass, so results are read against sex-specific ranges.
PCV stands for packed cell volume, also called haematocrit. It measures the percentage of your total blood volume that is made up of red blood cells.
MedlinePlus lists a typical adult range of about 37% to 48% for men and 34% to 43% for women. Ranges vary by lab, so use the range printed on your own report.
A low result generally points toward anaemia, ongoing blood loss, or a bone marrow that isn't producing enough red blood cells. Your doctor will interpret it alongside your symptoms and other test values.
Yes. Dehydration concentrates your blood, which can push PCV higher even though your actual number of red blood cells hasn't changed.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
No, though the two usually move together. Haemoglobin measures the oxygen-carrying protein inside red cells, while PCV measures what share of your blood volume the cells themselves take up.
Sometimes the question is specifically about red cell mass, such as tracking known anaemia or checking hydration status. A single PCV value can answer that without repeating a longer panel.