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Glossary
Haematocrit

Haematocrit

The share of blood volume made up of red cells. Normal is roughly 40 to 50 percent; in polycythaemia vera treatment aims to keep it under 45 percent, because above that clots become much more likely.

Overview Connected2

Overview

Haematocrit is measured on every full blood count. In polycythaemia vera it is the number treatment is steered by: the CYTO-PV trial showed that a target below 45 percent, compared with 45 to 50 percent, cut cardiovascular deaths and major clots by about two thirds. Some experts use a lower target of 42 percent in women, whose normal range is lower.

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Polycythaemia vera (PV)

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ProvenanceLast edited 2026-09-16 · Jude Gomila · Polycythaemia vera · diff · file

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