Hemoglobin vs Hematocrit / PCV: what's the difference?
Educational — not medical advice · Ranges vary between laboratories
The short answer: Hemoglobin measures the oxygen-carrying protein inside your red blood cells, in g/dL. Hematocrit measures the percentage of your blood volume those cells take up. They describe the same red cell supply from two angles, so they almost always move together.
Hemoglobin is the iron-rich protein inside red blood cells that picks up oxygen in the lungs and delivers it everywhere else. Tiredness, breathlessness on stairs, and pale skin are classic signs when it runs low.
Full Hemoglobin guidePicture your blood spun in a centrifuge until the red cells settle to the bottom of the tube - hematocrit is simply the percentage that layer takes up. It's a quick, low-cost way to judge whether you have enough red cells relative to your total blood volume.
Full Hematocrit / PCV guideAt a glance
| Hemoglobin | Hematocrit / PCV | |
|---|---|---|
| Panel | Complete blood count | Complete blood count |
| Unit | g/dL | % |
| Typical adult range | Normal 12–16.5 g/dL | Normal 34–50 % |
| Also known as | Hb, Haemoglobin, HGB | Packed Cell Volume, HCT, Hematocrit |
General adult reference intervals — your lab's printed range takes precedence.
Why they're often tested together
Both come from the same complete blood count, and a low value in either points toward anemia — iron deficiency being the usual cause. Both are also affected by fluid balance: dehydration concentrates the blood and lifts both, while extra fluid dilutes them.
Questions people ask
Why report both if they move together?
They're measured differently — hemoglobin chemically, hematocrit as the share of the sample the red cells occupy — so having both offers a cross-check. Hematocrit also feeds other calculated red cell indices printed on the same report.
What lifts both without anemia being involved?
Dehydration at the time of the draw is the common one, since less plasma makes the red cell share look higher. Smoking and living at high altitude also nudge both up, as the body makes more red cells in response to lower oxygen.
More comparisons
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